TW201947316A - Phase shift blankmask - Google Patents

Abstract

A phase-shift film according to the present disclosure includes layers different in composition, which can be etched by one etchant, and is formed as a continuous film or a multi-layered film having at least two layers by stacking layers of different compositions one or more times. Thus, transmittance, phase-shift amount and uniformity of a phase-shift film pattern are secured by not only reducing the thickness of the phase-shift film but also making a cross-section slope steep at an edge portion to get a clear boundary of a phase-shift film pattern when the phase-shift film is patterned by taking the variables into account, thereby providing a phase-shift blankmask and photomask improved in pattern precision of an object to be printed and the phase-shift film pattern.

Description

Phase shift blank mask and reticle

[Cross Reference of Related Applications] This application claims the priority of Korean Patent Application No. 10-2018-0052387, filed with the Korean Intellectual Property Office on May 8, 2018, the disclosure of which is incorporated herein by reference.

The present invention relates to a phase-shift blank mask and photomask, and more particularly to such a phase-shift blank mask and photomask, in which light passes through a phase shift phenomenon of exposure light with respect to a compound wavelength in a range of 290 nm to 450 nm. The pattern accuracy of carved objects is improved.

Used in the manufacture of thin film transistor (TFT) -liquid crystal display (LCD), organic light emitting diode (OLED), plasma display panel (PDP) ) And other flat panel display (FPD) devices or semiconductor integrated circuit (IC) devices in the photolithography process, a photomask made of a blank mask is usually used to transfer the pattern.

A blank mask refers to the formation of a thin film containing a metal material on the main surface of a transparent substrate made of synthetic quartz glass or the like, and a resist film is formed on the film; a photomask refers to a thin film in such a blank mask Be patterned. Here, the thin film is classified into a light-shielding film, an anti-reflection film, a phase shift film, a translucent film, a hard film, and the like according to optical characteristics, and two or more of these films may be combined to have two or more feature.

With the recent market demand for high-quality and high-performance FPD products, its application range has become wider, and advanced manufacturing process technology needs to be developed. In other words, technologies for high pattern resolution and high precision are needed to improve the integration degree in FPD devices (for example, semiconductor devices with high integration degree).

Therefore, as a method of improving the accuracy of a photomask for manufacturing an FPD device, a phase-shift blank mask and a photomask for FPD have been developed, which include such a phase-shifting film, even when exposed at a magnification of 1: 1 In the system, the phase shift film has a phase shift of about 180 ° with respect to the exposure light having a composite wavelength. The phase shift film refers to a thin film made of a molybdenum silicide (MoSi) compound or a chromium (Cr) compound, in which a thin film formed on a large-sized substrate is manufactured in a pattern form by wet etching.

A phase shift film made of a molybdenum silicide (MoSi) compound or a chromium (Cr) compound is isotropically etched by wet etching suitable for a large-sized substrate, so the cross section at the etched edge of the phase shift film pattern is formed as Has a gentle slope. This inclination at the edge of the pattern causes differences in the transmittance and the amount of phase shift between the edge portion of the pattern and other portions, thereby affecting the uniformity of the line width in the phase shift film pattern. In addition, the inclination of the edge portion of the phase shift film makes the phase shift film have an unclear boundary and makes it difficult to form a fine pattern.

In addition, the phase shift film is required to have a low reflectance, because when the phase shift film has a high reflectance, interference between light reflected from the film surface and exposure light makes it difficult to form a fine pattern in a photolithography process.

Therefore, an aspect of the present disclosure is to provide a phase shift blank mask and a photomask, wherein a cross section at an edge of a phase shift film pattern has a good inclination. In this way, the transmittance and the uniformity of the phase shift amount around the pattern edge region are excellent, thereby improving the accuracy and uniformity of the pattern line width of the lithographic object.

Another aspect of the present disclosure is to provide a phase-shift blank mask and a photomask, wherein the reflectance of the surface of the phase-shift film is reduced to prevent interference caused by light reflected from the surface, thereby improving the fine pattern of the lithographic object. Precision.

According to one embodiment of the present disclosure, there is provided a phase shift blank mask having a phase shift film on a transparent substrate, wherein the phase shift film includes a multilayer film including at least two metal silicide-containing layers, and The topmost layer of the multilayer film contains more nitrogen (N) than at least one lower layer.

The layer of the phase shift film may include molybdenum silicide (MoSi), or a compound containing one of oxygen (O), nitrogen (N), and carbon (C) in addition to molybdenum silicide (MoSi). Or multiple elements.

The layer of the phase shift film may contain nitrogen (N), the content of nitrogen is uniform, or the content of nitrogen decreases from the topmost layer to the transparent substrate.

The phase shift film can be etched with an etchant mainly containing ammonium hydrogen fluoride ((NH ₄ ) HF ₂ ), hydrogen peroxide (H ₂ O ₂ ), and deionized water.

The content of ammonium bifluoride ((NH ₄ ) HF ₂ ) in the entire etchant may not exceed 10% by volume (vol%).

Relative to the exposure light with a compound wavelength in the range of 290 nm to 450 nm, the phase shift film can have a transmittance of 1% to 40%, a phase shift amount of 140 ° to 220 °, and a deviation of the phase shift amount not greater than 60 ° .

Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings. However, these examples are provided for illustrative purposes only and should not be construed as limiting the scope of the invention. Therefore, those of ordinary skill in the art will understand that various modifications and equivalents can be made from these embodiments. Furthermore, the scope of the invention must be defined in the appended claims.

Hereinafter, a phase-shift blank cover and a photomask realized according to an embodiment of the present disclosure are used to manufacture a thin film transistor (TFT) -liquid crystal display (LCD), an organic light emitting diode (OLED), and a plasma display panel. (PDP) and other flat-panel display (FPD) devices or phase shift blank masks and photomasks for semiconductor devices. In addition, the exposure light refers to light having a complex wavelength in a range of 290 nm to 450 nm.

FIG. 1 illustrates a cross-sectional view of a phase-shift blank mask according to a first embodiment of the present disclosure, and FIG. 2 illustrates a cross-sectional view of a phase-shift film according to an embodiment of the present disclosure.

Referring to FIG. 1, a phase shift blank mask 100 according to the present disclosure has a structure in which a phase shift film 104, a light shielding film 110, and a resist film 114 are sequentially stacked on a transparent substrate 102.

The transparent substrate 102 may refer to a rectangular transparent substrate, for example, one side of which has a length of 300 mm or more, and may include a synthetic quartz glass substrate, a soda lime glass substrate, a non-flammable glass substrate, a low thermal expansion glass substrate, and the like.

As shown in FIG. 2, the phase shift film 104 has a structure in which at least two layers, preferably two to ten layers, more preferably two to eight layers of films 104 a... 104 n are laminated.

Each of the thin films 104a ... 104n configured to form the phase shift film 104 is formed of only a metal silicide, or a compound containing oxygen (O), nitrogen (N), At least one light element among carbon (C), boron (B), and hydrogen (H).

In the metal silicide and its compound, the metal includes one or more selected from the group consisting of aluminum (Al), cobalt (Co), tungsten (W), molybdenum (Mo), vanadium (V), and palladium (Pd), titanium (Ti), platinum (Pt), manganese (Mn), iron (Fe), nickel (Ni), cadmium (Cd), zirconium (Zr), magnesium (Mg), lithium (Li), selenium (Se), copper (Cu), yttrium (Y), sulfur (S), indium (In), tin (Sn), boron (B), beryllium (Be), sodium (Na), tantalum (Ta), thorium (Hf) and niobium (Nb).

Specifically, for each thin film 104a ... 104n configured to form the phase shift film 104, it may be formed of one or more compounds selected from the group consisting of: molybdenum silicide containing molybdenum (Mo) (MoSi) and its compounds, such as MoSiO, MoSiN, MoSiC, MoSiON, MoSiCN, MoSiCO, and MoSiCON.

A molybdenum silicide (MoSi) compound film may contain 2 to 30 atom% of molybdenum (Mo), 20 to 70 atom% of silicon (Si), 5 to 50 atom% of nitrogen (N), 0 atom % To 30 atomic% of oxygen (O) and 0 to 30 atomic% of carbon (C).

Each of the thin films 104a ... 104n configured to form the phase shift film 104 may have one composition or different compositions including different light elements. For example, when the phase shift film includes two layers, the MoSiN layer and the MoSiN layer may constitute a phase shift film, or the MoSiN layer and the MoSiON layer may constitute a phase shift film. In addition, when the layers have the same composition, the element composition ratios of the layers may be different.

For each thin film 104a ... 104n configured to form the phase shift film 104, it may be configured as a single film having a composition or a composition ratio, or as a continuous film in which the composition or the composition ratio is Change. Continuous film refers to a film formed by changing process parameters such as reaction gas, power, and pressure during a sputtering process in which a plasma is present.

The films 104a ... 104n configured to form the phase shift film 104 have different etching rates and surface reflectances for the same etchant depending on variables such as composition, composition ratio, thickness, etc., so these variables can be considered by Thereby, it is appropriately arranged so that when the phase shift film is patterned, the slope of the cross section at the edge of the pattern is steep and the reflectance is adjusted.

First, as a method of making the cross-sectional slope steep by adjusting the etching rate of the phase shift film 104, the content of light elements can be controlled. Specifically, as the content of nitrogen (N) or carbon (C) in the light element increases, the etching rate becomes slower, and as the content of oxygen (O) increases, the etching rate becomes faster.

Specifically, when the etching rate is controlled by changing the content of nitrogen (N) or carbon (C), the films 104a ... 104n of the phase shift films are structured such that the nitrogen (N) or The content of carbon (C) is higher than the content of nitrogen (N) or carbon (C) in at least one of the underlying films, or the content of nitrogen (N) or carbon (C) in the film adjacent to the transparent substrate is lower than some Content of nitrogen (N) or carbon (C) in the upper film. For example, from the top film to the bottom film, the content of nitrogen (N) or carbon (C) decreases, so the cross section at the edge of the pattern is improved to be more vertical.

On the other hand, unlike nitrogen (N) or carbon (C), in the case of oxygen (O), the oxygen (O) content of the uppermost film in the film may be lower than the oxygen content of at least a lower film, or it is transparent with The oxygen (O) content of the film adjacent to the substrate may be higher than the oxygen (O) content of an upper film. For example, from the top film to the bottom film, the oxygen (O) content is increased, so the cross section at the edge of the pattern is improved to be more vertical. Meanwhile, in terms of reflectance, since the uppermost film contains more oxygen, the reflectance becomes lower. The reflectance of the phase shift film 104 can be adjusted by changing the content of one of nitrogen (N) and oxygen (O) or both in the films 104a ... 104n. In particular, reflection can be reduced by increasing the content of nitrogen (N) and oxygen (O). However, oxygen (O) increases the etch rate, and thus the etch rate is increased compared to the reduced reflectance, thereby making the cross-section slope at the edges gentle and worse. Therefore, the thin films 104a ... 104n included in the phase shift film are controlled so that the oxygen content does not exceed 30 atom% or preferably does not exceed 20 atom%, and the thickness does not exceed 30 nm.

Therefore, when arranging the thin films 106a ... 106n according to the present disclosure, it is not limited to the above-mentioned nitrogen (N), carbon (C), and oxygen (O) considering only the etched shape of the cross section of the phase shift film 104 Etching characteristics can be arranged by considering all optical characteristics such as reflectance. That is, the following aspects are considered: the types of film growth gases used to form the thin films 106a ... 106n; the etching rate and reflection due to differences in nitrogen (N), carbon (C), and oxygen (O) content in the thin film Rate; etc., so that different films 106a ... 106n are stacked in such a way that a film arranged at a specific portion can be configured to have an etching rate or reflectance lower or higher than that provided on the film or The etch rate or reflectivity of the other thin film underneath optimizes the etched cross section and reflectivity. For this reason, when the thin films 106a ... 106n are formed, in the film growth gas, the injection amount of the film growth gas containing nitrogen (N), carbon (C), and oxygen (O) is appropriately adjusted to give the films similar or different The etching rate and reflectivity of the films 106a ... 106n are adjusted to the optimal state.

The total thickness of the phase shift film is 500 Å to 1,500 Å, and preferably 900 Å to 1,400 Å. In consideration of adhesiveness and etching characteristics for the films disposed above and below, the thin films 104a ... 104n configured to form the phase shift film 104 have a thickness of 50 Å to 1,450 Å.

The film forming the phase shift film can be etched with an etchant.

The etchant of the phase shift film may be an etchant mainly containing ammonium bifluoride ((NH ₄ ) HF ₂ ), hydrogen peroxide (H ₂ O ₂ ), and deionized water. In the main component of the etchant, the content of ammonium bifluoride ((NH ₄ ) HF ₂ ) does not exceed 10% by volume, and preferably does not exceed 5% by volume. This is because when the ammonium bifluoride ((NH ₄ ) HF ₂ ) is contained in an amount exceeding 10% by volume, the surface of the substrate is damaged when the phase shift film is etched.

The phase shift film 104 has a reflectance of not higher than 35% with respect to exposure light having a composite wavelength in a range of 290 nm to 450 nm. In addition, the phase shift film 104 has the lowest reflectance at a certain wavelength in a wavelength range of 400 nm to 900 nm, and preferably has the lowest reflectance at a certain wavelength in a wavelength range of 500 nm to 800 nm.

The phase shift film 104 has a transmittance of 1% to 40%, preferably 5% to 20% with respect to exposure light having a composite wavelength in a range of 290 nm to 450 nm. In addition, for exposure light having a composite wavelength in the range of 290 nm to 450 nm, the phase shift film 104 has a phase shift amount of 140 ° to 220 ° and a phase shift amount deviation of not more than 60 °. Here, the transmittance deviation and the phase shift amount deviation mean the difference between the maximum value and the minimum value of the value of the exposure light corresponding to the composite wavelength in the range of 290 nm to 450 nm.

The light-shielding film 110 is disposed on the phase shift film 104, and because it is made into a pattern form when the mask is manufactured, it is used as an etching mask for patterning the phase shift film 104.

The light shielding film 110 may include one or more of the following metal materials: chromium (Cr), aluminum (Al), cobalt (Co), tungsten (W), molybdenum (Mo), vanadium (V), palladium (Pd), titanium (Ti), platinum (Pt), manganese (Mn), iron (Fe), nickel (Ni), cadmium (Cd), zirconium (Zr), magnesium (Mg), lithium (Li), selenium (Se), copper (Cu), yttrium (Y), sulfur (S), indium (In), tin (Sn), boron (B), beryllium (Be), sodium (Na), tantalum (Ta), hafnium (Hf), niobium (Nb) and silicon (Si), or in addition to these metal materials, one or more materials of nitrogen (N), oxygen (O), and carbon (C) may be included.

The light-shielding film 110 may preferably contain only chromium (Cr), or one or more compounds selected from compounds containing oxygen (O), nitrogen (N), and carbon in addition to chromium (Cr). (C) One or more elements, such as CrO, CrN, CrC, CrCN, CrCO, and CrCON.

The light-shielding film 110 is provided in the form of a continuous film or in the form of a multilayer film including two or more light-shielding layers 106 and an anti-reflection layer 108. When the light shielding layer 106 has an anti-reflection function, the anti-reflection layer 108 may be omitted.

The light-shielding film 110 may be in the form of a continuous film, or in the form of a multilayer film including two or more layers that are laminated one or more times, these layers are made of a material that can be etched by the same etchant, and have different compositions Or composition ratio. In this case, the thin films forming the light-shielding film 110 have different etching rates for the same etchant according to variables such as composition, composition ratio, thickness, etc. Therefore, the above variables should be considered in order to arrange the films appropriately.

After the lower phase shift film 104 is patterned, the light-shielding film pattern formed by the light-shielding film 110 may be removed, or it may be left in a portion of the phase-shift film pattern that is required to define a blind region at the edge of the substrate.

The light shielding film 110 alone, or the laminated structure of the light shielding film 110 and the phase shift film 104 has an optical density of 2 to 6 with respect to the exposure light, and has a thickness of 500 Å to 2,000 Å. In addition, the reflectance of the light shielding film 110 with respect to the exposure light is not higher than 30%, preferably not higher than 20%, and more preferably not higher than 15%.

As described above, the present invention uses molybdenum silicide (MoSi) or a compound thereof to form a phase shift film as a multilayer film, and the etching rates of the layers of the multilayer film are different from each other, thereby improving the cross-sectional slope at the edges of the phase shift film pattern . In addition, the reflectance can be reduced by controlling the content of oxygen and nitrogen in the uppermost layer.

Therefore, the phase shift film pattern is improved in critical dimension (CD) accuracy and uniformity, so that a fine phase shift film pattern not larger than 2 μm, preferably not larger than 1.8 μm, and more preferably not larger than 1.5 μm can be realized.

Although not shown, the phase-shift blank mask of the present disclosure may further selectively include one or more metal films above and below the phase-shift film or light-shielding film, and the metal film may be a semi-transmissive film, an etch Stop layer and one of the etch masks.

3A to 3F are sectional views for explaining a method of manufacturing a phase shift mask and a phase shift mask according to the first embodiment of the present disclosure.

Referring to FIG. 3A, for a phase shift mask according to the present disclosure, a phase shift blank mask 100 is formed by sequentially stacking a phase shift film 104, a light shielding film 110, and a resist film 114 on a transparent substrate 102.

The phase shift film 104 and the light-shielding film 110 can be grown by a reactive magnetron sputtering method.

In this case, by using at least one reactive gas of NO, N2O, N2, O2, CO2, CO, and CH4, and freely used in addition to the reactive gas, oxygen (O) and nitrogen (N) can be provided. And carbon (C) gas to form a phase shift film 104 and a light-shielding film 110.

When the thin film of the phase shift film 104 is made of molybdenum silicide (MoSi) or a compound thereof, a single molybdenum silicide (MoSi) target or multiple molybdenum (Mo) targets and silicon (silicon) can be used by a sputtering process. Si) target to form a phase shift film 104. In this case, a single molybdenum silicide (MoSi) target has the following composition ratio Mo: Si = 2 atomic% to 30 atomic%: 70 atomic% to 98 atomic%, for example, various composition ratios, such as Mo: Si = 10 atomic %: 90 atomic%, Mo: Si = 15 atomic%: 85 atomic%, Mo: Si = 20 atomic%: 80 atomic%, Mo: Si = 30 atomic%: 70 atomic%, and the like. The composition ratio of the target can be freely adjusted according to the required conditions of the phase shift film 104.

In order to control the etching rate of the thin film configured to form the phase shift film 104, the ratio of the gas injected during the sputtering process can be changed, and the ratio of the reactive gas and the inert gas can be fine-tuned to 0.5: 9.5 ~ 4: 6, preferably 1: 9 ~ 3: 7.

The light shielding film 110 may be formed by a laminated structure of the light shielding layer 106 and the anti-reflection layer 108. However, this structure is only exemplary. Alternatively, in consideration of wet etching characteristics, the light shielding film 110 may be formed of a continuous film or a multilayer film including two or more layers.

The light shielding film 110 is made of a material having an etch selectivity with respect to the phase shift film 104, such as one of chromium (Cr) and a Cr compound, such as CrO, CrN, CrC, CrCO, CrON, CrCN, and CrCON .

Referring to FIG. 3B, processes such as exposure, development, etc. are performed on the resist film to form a resist film pattern 114a, and the resist film pattern 114a is used as an etching mask to etch the lower light-shielding film, thereby forming a light-shielding film pattern 110a.

Referring to FIG. 3C, the lower phase shift film is etched using the resist film pattern and the light-shielding film pattern 110a as an etching mask, thereby forming a phase shift film pattern 104a of a multilayer film.

Although not shown, the resist film pattern may be removed during the process, and then the light-shielding film pattern 110a is used as an etching mask to etch the lower phase shift film, thereby forming a phase shift film pattern 104a of a multilayer film.

In this case, the etching process for forming the light-shielding film pattern 110a and the phase shift film pattern 104a may be implemented by one of a wet etching method and a dry etching method, and may preferably be implemented by a wet etching method. Here, when the thin film of the phase shift film 104 is provided in the form of molybdenum silicide (MoSi) or a compound thereof, the wet etching method may employ ammonium bifluoride ((NH ₄ ) HF ₂ ), hydrogen peroxide (H ₂ O) ₂ ) and etchant of deionized water. In addition, the etchant and the etching method used in the wet etching process can be realized by various known materials and methods.

Referring to FIG. 3D, after a resist film pattern (not shown) is formed on the light-shielding film pattern, an etching process is performed on the light-shielding film pattern, so that the light-shielding film pattern 110b remains on the phase-shifting film pattern 104a, thereby manufacturing a substrate having a contact for forming a contact. Phase shift mask 200 with a line-rim-type structure. Therefore, a side-lobe phenomenon of a phase shift can be prevented.

In addition, referring to FIG. 3E, the phase shift mask 200 may be configured such that the light shielding film pattern 110 b remains at an edge portion of the phase shift film pattern 104 a to define a blind area.

In addition, referring to FIG. 3F, the phase shift mask 200 may be configured such that after the above-mentioned stage of FIG. 3B, the light-shielding film pattern on the phase shift film pattern 104 a is completely removed, so that the phase shift film is retained only on the transparent substrate 102. Pattern 104a.

FIG. 4 illustrates a cross-sectional view of a phase shift mask according to a second embodiment of the present disclosure.

Referring to FIG. 4, a phase shift mask 300 according to the present disclosure includes a phase shift film pattern 104 a having a multilayer film of two or more layers on a main region of a transparent substrate 102, and at least a light-shielding film pattern 110 b located in a blind region, The light-shielding film pattern 110b has an auxiliary pattern such as an alignment key.

For the phase shift mask 300, a light-shielding film and a resist film pattern are formed on the transparent substrate 102, and then the light-shielding film is etched using the resist film pattern as an etching mask, thereby forming a light-shielding film pattern 110b.

Then, after a phase shift film is formed on the transparent substrate 102 including the light shielding film pattern 110b, a plurality of phase shift films are etched, and a resist film pattern is formed on the phase shift film, thereby forming a phase shift film pattern 104a.

Although not shown, the light-shielding film pattern 110b may be partially disposed under the phase-shifting film pattern in a required main region.

The phase-shift blank mask according to one embodiment of the present disclosure may have a structure including a metal thin film that is used as an etching mask for a phase-shifting film on a multilayer phase-shifting film.

FIG. 5 illustrates a cross-sectional view of a phase-shift blank mask according to a third embodiment of the present disclosure.

Referring to FIG. 5, a phase shift blank mask 400 according to the present disclosure includes a phase shift film 204, a metal film 212, and a resist film 214 that are sequentially formed on a transparent substrate 202.

Here, the phase shift film 204 has the same structure and physical properties as the phase shift film according to the foregoing embodiment in structure, physical, chemical, and optical.

The metal film 212 is patterned to serve as an etch mask for the phase shift film 204. Therefore, the metal film 212 may be made of a material having an etching selectivity greater than "10" with respect to the etchant for the phase shift film 204.

The metal film 212 may include one or more of the following metal materials: chromium (Cr), aluminum (Al), cobalt (Co), tungsten (W), molybdenum (Mo), vanadium (V), palladium (Pd), titanium (Ti), platinum (Pt), manganese (Mn), iron (Fe), nickel (Ni), cadmium (Cd), zirconium (Zr), magnesium (Mg), lithium (Li), selenium (Se), copper (Cu), yttrium (Y), sulfur (S), indium (In), tin (Sn), beryllium (Be), sodium (Na), tantalum (Ta), hafnium (Hf), niobium (Nb), or In addition to these metal materials, one or more light elements of oxygen (O), nitrogen (N), and carbon (C) may be contained.

When the phase shift film 204 includes a molybdenum silicide (MoSi) compound, the metal film 212 may preferably include only chromium (Cr), or a chromium (Cr) compound, and the chromium (Cr) compound may further include chromium (Cr). Contains one or more light elements of oxygen (O), nitrogen (N), and carbon (C). In this case, the metal film 212 has the following composition ratios: 30 atomic% to 100 atomic% of chromium (Cr), 20 atomic% to 50 atomic% of nitrogen (N), and 0 atomic% to 30 atomic% of oxygen ( O), 0 atom% to 30 atom% of carbon (C).

The thickness of the metal film 212 is 10 Å to 700 Å, and preferably 50 Å to 400 Å. The adhesion between the metal film 212 and the resist film 214 disposed thereon is excellent, and since the metal film 212 is very thin, the resist film 214 used as an etching mask of the metal film 212 can be set to be thin and resistant to The etched film 214 has a thickness of not more than 8,000 Å, and preferably has a thickness of not more than 6,000 ，,

The phase shift blank mask 400 according to one embodiment of the present disclosure may be manufactured as a phase shift mask by the same process as the foregoing embodiment.

Here, the phase shift mask may have various structures as in the foregoing embodiment and shown in FIG. 3D, FIG. 3E, FIG. 3F, and FIG. 4, for example, a structure in which only a phase shift film pattern is provided on a transparent substrate. The structure of the metal film pattern remains on a part of the phase shift film pattern, and only the structure of the phase shift film pattern remains on the main area.

As such, according to the present disclosure, such a metal thin film is used as an etching mask for a phase shift film, and thus the resist film can be made much thinner than a conventional resist film. Accordingly, the loading effect is significantly reduced, so that the metal film pattern is formed very accurately after the etching process, and the phase shift film pattern etched by using the metal film pattern as an etching mask is also formed as a CD with high accuracy .

In addition, since the adhesion between the metal film and the resist film is excellent, when the phase shift film is patterned, the cross section of the phase shift film pattern is prevented from being inclined due to the penetration of the interface of the etchant.

In addition, although not shown, the phase shift mask may further include a light shielding film pattern disposed above or below the phase shift film pattern to have a predetermined function, such as a light blocking function and the like.

FIG. 6 illustrates a cross-sectional view of a boundary of a phase shift film pattern according to an embodiment of the present disclosure.

Referring to FIG. 6, the sidewall angle of the multilayer phase shift film pattern 104a according to the present invention is improved because variables such as thickness, etching rate, and the like are taken into consideration in the following structure: the lower film is formed to have a faster etching rate than the upper film Structures, structures that use thin films to make the etch rate slower in certain parts, and so on.

In this case, the horizontal distance (ie, the tail dimension d) between the upper and lower edges of the phase shift film pattern 104a is not more than 100 nm, and preferably not more than 60 nm. In addition, an angle (θ) of a straight line connecting the edges of the top surface and the bottom surface of the phase shift film pattern 104 a with respect to the top surface is 70 ° to 110 °, and preferably 80 ° to 100 °.

In addition, the phase shift blank mask and photomask according to the present disclosure may further include an etch stop film, a semi-transmissive film, a hard film, or the like in one or more portions above and below the phase shift film or the light shielding film. .

[ implementation plan ]

Molybdenum silicide MoSi ) Manufacturing and testing of multilayer phase shift films for compounds

According to one embodiment of the present disclosure, a method of manufacturing a phase-shift blank mask will be described in which a phase-shift film and a light-shielding layer are sequentially stacked on a transparent substrate.

First, prepare a synthetic quartz glass substrate with a size of 800 mm ´ 920 mm. Using a DC magnetron sputtering device, a MoSi target (10 atomic%: 90 atomic%) was used to form a three-layer phase shift film on a substrate. Specifically, the first layer adjacent to the transparent substrate was grown under the condition of Ar: N2 = 90:18 sccm and the process power was 1.6kW, and was grown under the condition of Ar: N2 = 90: 22sccm and the process power was 1.7kW. The second layer was grown under the conditions of Ar: N2 = 90: 24sccm and process power of 1.75kW. The thickness of the phase shift film deposited as described above was measured. The thickness of the first film was 34.5 nm, the thickness of the second film was 35.2 nm, the thickness of the third film was 33.8 nm, and their total thickness was 103.5 nm.

In this case, referring to FIG. 7, which shows the reflectance and transmittance according to one embodiment of the present disclosure, the transmittance of i-line is 4.65%, the transmittance of h-line is 7.52%, and the transmittance of g-line The rate was 10.10%, and the transmittance deviation of the ihg line was 5.45%. In addition, the reflectance of the i-line is 21.45%, the reflectance of the h-line is 22.01%, the reflectance of the g-line is 21.39%, and there is a minimum reflectance at 604 nm.

Meanwhile, the phase shift amount of the i-line is 182 °, the phase shift amount of the h-line is 168 °, the phase shift amount of the g-line is 153 °, and the phase shift amount deviation is 29 °.

Then, a double-layer light-shielding film having a thickness of 105 nm was formed using a chromium (Cr) target. The optical density was measured after the light-shielding film was formed, and the optical density of the i-line was measured to be 3.5, so there was no problem using it as a light-shielding film.

Then, the light-shielding layer is covered with a resist film having a thickness of 500 nm, thereby finally completing the manufacture of the phase-shift blank mask.

Using the blank mask manufactured as described above, a photomask was manufactured as described below.

First, a blank mask is used to pattern the resist film through exposure and development, and then the resist film pattern is used as an etching mask to wet-etch the underlying light-shielding layer pattern.

Then, the resist film is removed, and the phase shift film is wet-etched again using the light-shielding layer pattern. Here, an etchant containing ammonium hydrogen fluoride, hydrogen peroxide, and deionized water was used as an etchant for the phase shift film. Then, the resist film is covered again, the main area except the peripheral blind area is exposed and developed, and the light-shielding layer in the main area is completely removed, thereby finally completing the manufacture of the photomask.

The cross-section of the photomask pattern manufactured as described above was measured by FE-SEM to obtain the side wall angle of the cross-section. Referring to FIG. 8, which shows a picture of a cross section of a photomask pattern according to one embodiment of the present disclosure, it will be understood that the cross section of the phase shift film pattern of the photomask is made more vertical than about 80 °.

[ Comparative example #1]

Molybdenum silicide MoSi ) Manufacturing and testing of single-layer phase shift films for compounds

For comparison with the foregoing embodiment, Comparative Example # 1 manufactured and tested a single-layer phase shift film.

Using the same substrate and device as the embodiment and the same MoSi target (10 atomic%: 90 atomic%), the film was grown as a single unit under the film growth conditions of the process gas Ar: N ₂ = 90 sccm: 24 sccm and the process power of 1.75 kW. The phase shift film according to Comparative Example # 1 was a phase shift film having a thickness of 109 nm.

In this case, referring to FIG. 9, which shows the reflectance and transmittance according to Comparative Example # 1, the i-line transmittance is 3.55%, the h-line transmittance is 6.43%, and the g-line transmittance is 8.38%, and the phase shifts of the lines are 190.6 °, 174.1 °, and 162.7 °. Therefore, there is no problem in using it as a phase shift film with a composite wavelength.

Then, as in the embodiment, a light-shielding film is formed using a chromium (Cr) target, and then a resist film having a thickness of 500 nm is covered, thereby completing the manufacture of a phase-shift blank mask. In addition, a mask manufacturing process is performed as in the embodiment, and then a cross section of the mask pattern is measured by FE-SEM, thereby obtaining a side wall angle of the cross section.

In this case, referring to FIG. 10, which shows a picture of a cross-section of a photomask pattern according to Comparative Example # 1, it can be understood that the cross-section of the single-layer phase shift film pattern of the photomask has a relative of about 60 ° Poor cross-section pattern.

[ Comparative example #2]

According to molybdenum silicide ( MoSi ) Manufacturing and testing of multi-layer phase shift films with chemical composition

Comparative Example # 2 produced a multilayer phase shift film by lowering the content of nitrogen (N) from bottom to top, and formed a photomask to evaluate the cross-sectional shape of the phase shift film pattern.

To this end, the same substrate and device as the embodiment and the same MoSi target [10 atomic%: 90 atomic%] are used to form a three-layer phase shift film,

Specifically, the first layer adjacent to the transparent substrate was grown under the condition of Ar: N2 = 50: 50sccm and the process power was 1.2kW, and was grown under the condition of Ar: N2 = 90: 26sccm and the process power was 1.35kW. The second layer, the third layer was grown under the conditions of Ar: N2 = 90: 18sccm and process power of 1.45kW.

In this case, referring to FIG. 11, which shows the reflectance and transmittance according to Comparative Example # 2, the transmittance of i-line is 4.35%, the transmittance of h-line is 6.91%, and the transmittance of g-line is 9.27%; ihg line's throw rate deviation is 4.92%; and i-line phase shift amount is 181 °, h-line phase shift amount is 165 °, and g-line phase shift amount is 151 °, thus showing Results similar to the examples.

However, as the nitrogen content in the reflecting surface decreases, the reflectance of the i-line is 33.35%, the reflectance of the h-line is 33.33%, and the reflectance of the g-line is 33.13%, which is relatively more than those in the embodiment It is approximately 30% higher, thus exhibiting high reflectivity to all wavelengths.

Then, as in this embodiment, a light-shielding film is formed using a chromium (Cr) target, and then a resist film having a thickness of 500 nm is covered, thereby completing the manufacture of a phase-shift blank mask.

In addition, a mask manufacturing process is performed as in the embodiment, and then a cross section of the mask pattern is measured by FE-SEM, thereby obtaining a side wall angle of the cross section.

In this case, referring to FIG. 12, which shows a picture of a cross-section of a mask pattern according to Comparative Example # 2, it can be understood that the cross-section of the multilayer phase shift film pattern of the mask has the worst Section pattern. It is believed that this result is due to a lower nitrogen (N) content in the uppermost layer and a higher nitrogen (N) content in the lower layer.

According to the present disclosure, a phase shift film is formed of a multilayer structure including two or more layers, and each film may be realized by a single film or a continuous film. In addition, the cross-sectional shape at the edges of the pattern and the reflectance can be controlled by controlling the content of oxygen, nitrogen, and carbon in each layer forming the phase shift film.

Therefore, the edge cross-sectional shape of the phase shift film pattern of the phase shift blank mask and the photomask can be improved. In addition, the transmittance and the uniformity of the phase shift amount in the pattern edge region are improved, thereby improving the accuracy and uniformity of the line width of the phase shift film pattern and the pattern in the lithographic object.

In addition, according to the present disclosure, a phase shift blank mask and a photomask are manufactured by reducing the reflectance on the surface of the phase shift film and suppressing interference waves generated by light reflected from the surface, thereby improving light Fine pattern accuracy of carved objects.

Although the present disclosure has been shown and described with the exemplary embodiments, the technical scope of the present disclosure is not limited to the scope disclosed in the foregoing embodiments. Therefore, those of ordinary skill in the art will understand that various changes and modifications can be made by these exemplary embodiments. Further, as defined in the appended claims, it is apparent that these changes and modifications are included in the technical scope of the present disclosure.

100, 400‧‧‧phase shift blank screen

102, 202‧‧‧ transparent substrate

104, 204‧‧‧ phase shift film

104a, 104b, 104c, 104n‧‧‧ film

106‧‧‧ shading layer

108‧‧‧Anti-reflective layer

110‧‧‧Light-shielding film

114, 214‧‧‧ resist

114a‧‧‧ resist pattern

110a, 110b ‧‧‧ light-shielding film pattern

200, 300‧‧‧ phase shift mask

212‧‧‧metal film

d‧‧‧size

θ‧‧‧ angle

The above aspects and / or other aspects will become clearer and easier to understand through the following description of exemplary embodiments in conjunction with the accompanying drawings, in which: FIG. 1 illustrates a phase shift blank mask according to a first embodiment of the present disclosure 2A is a cross-sectional view of a phase shift film according to an embodiment of the present disclosure; FIGS. 3A to 3F are views for explaining a phase shift mask manufacturing method according to a first embodiment of the present disclosure and the A cross-sectional view of a phase-shifting mask; FIG. 4 shows a cross-sectional view of a phase-shifting mask according to a second embodiment of the present disclosure; FIG. 5 shows a 6 is a cross-sectional view of a boundary of a phase shift film according to the present disclosure; FIG. 7 is a graph showing reflectance and transmittance according to an embodiment of the present disclosure; A photograph of a cross-section of a mask pattern according to one embodiment of the present invention; FIG. 9 shows a graph of reflectance and transmittance according to Comparative Example # 1; FIG. 10 shows a graph of a reflectance according to Comparative Example # 1. A cover of a sectional pattern; FIG. FIG. 11 shows a # transmittance and reflectance according to Comparative Example 2; and FIG. 12 shows a cross section of Comparative Example 2 # reticle pattern photograph.

Claims (18)

A phase shift blank cover has a phase shift film on a transparent substrate, wherein the phase shift film includes a multilayer film including at least two layers containing a metal silicide, and the most of the multilayer film The top layer contains more nitrogen than at least one lower layer. The phase-shift blank mask according to item 1 of the scope of the patent application, wherein the layer in the phase-shift film contains molybdenum silicide or a compound containing oxygen, nitrogen, and One or more elements of carbon. The phase-shift blank mask according to item 1 of the scope of patent application, wherein the metal includes one or more selected from the group consisting of aluminum, cobalt, tungsten, molybdenum, vanadium, palladium, titanium, platinum, Manganese, iron, nickel, cadmium, zirconium, magnesium, lithium, selenium, copper, yttrium, sulfur, indium, tin, boron, beryllium, sodium, tantalum, hafnium and niobium. The phase shift blank mask according to item 2 of the scope of patent application, wherein the layer in the phase shift film contains 2 atomic% to 30 atomic% of molybdenum, 20 atomic% to 70 atomic% of silicon, and 5 atomic% to 50 atomic% of nitrogen, 0 atomic% to 30 atomic% of oxygen, and 0 to 30 atomic% of carbon. The phase shift blank cover as described in the first scope of the patent application, wherein the layers in the phase shift film have one composition, or have one composition but have different composition ratios, or have different compositions and these compositions are in Contains one or more elements of oxygen, nitrogen and carbon. The phase-shift blank mask according to item 1 of the scope of patent application, wherein the layer in the phase-shift film contains nitrogen, and the nitrogen content is uniform, or from the topmost layer to the transparent substrate, so The nitrogen content is reduced. The phase shift blank cover according to item 1 of the scope of patent application, wherein in the layer of the phase shift film, a nitrogen content in a layer adjacent to the transparent substrate is less than a nitrogen content in at least one of the upper layers. The phase shift blank cover according to item 1 of the scope of patent application, wherein the oxygen content of the topmost layer in the layers of the phase shift film is less than the oxygen content of at least one of the lower layers or adjacent to the transparent substrate The oxygen content in the layer is higher than that of a certain upper layer. The phase shift blank cover described in item 8 of the scope of patent application, wherein when the topmost layer of the phase shift film contains oxygen, its oxygen content does not exceed 30 atomic%, and the topmost layer has no greater than 30 nm thickness. The phase shift blank cover according to item 8 of the scope of patent application, wherein the carbon content in the topmost layer in the layer of the phase shift film is higher than the carbon content in at least one of the lower layers, or is transparent to the The carbon content of adjacent layers of the substrate is less than the carbon content of a certain upper layer. The phase shift blank cover described in item 8 of the scope of patent application, wherein the thickness of the phase shift film is 500 Å to 1,500 Å, and the thickness of each layer in the phase shift film is 50 Å to 1,450 Å. The phase shift blank mask according to items 1 to 11 of the scope of the patent application, wherein the phase shift film is etched by an etchant mainly containing ammonium hydrogen fluoride, hydrogen peroxide, and deionized water. The phase-shift blank mask according to item 12 of the scope of patent application, wherein the content of ammonium bifluoride in all the etchant is not more than 10% by volume. According to the phase shift blank mask described in the first item of the patent application scope, the reflectance of the phase shift film is not higher than 35% with respect to the exposure light having a composite wavelength in the range of 290 nm to 450 nm. The phase-shift blank mask described in the first item of the patent application range, wherein the phase-shift film has the lowest reflectance with respect to a wavelength in a range of 400 nm to 900 nm. According to the phase shift blank mask described in item 1 of the scope of patent application, the phase shift film has a transmittance of 1% to 40% with respect to exposure light having a composite wavelength in a range of 290nm to 450nm. The phase-shift blank mask according to item 1 of the scope of patent application, wherein the phase-shift film has a phase shift amount of 140 ° to 220 ° with respect to exposure light having a composite wavelength in a range of 290 nm to 450 nm, and the phase The deviation of the displacement is not more than 60 °. The phase-shift blank mask described in item 1 of the scope of patent application, further comprising one or more films in a light-shielding film, a translucent film, an etch stop film, and an etch mask located above or below the phase-shift film.