KR20070060529A - Blank mask with antireflective film and manufacturing method thereof and photomask using the same - Google Patents

Abstract

A blank mask with an ARC(Anti-Reflective Coating), a method for manufacturing the same, and a photomask using the same are provided to reduce reflectivity in KrF and ArF excimer laser exposure wavelength by using an improved ARC structure. A blank mask includes a phase shift layer(2) and a light shielding layer on a transparent substrate(1), wherein the phase shift layer is mainly made of metal or metal compound. ARCs are capable of being formed on the phase shift layer, the light shielding layer or the transparent substrate. At this time, the ARCs are made of the same metal based material.

Description

Blank Mask with Anti-Reflection Film, Manufacturing Method and Photomask Using the Same {Blank Mask with Antireflective Film and Manufacturing Method Thereof and Photomask Using the Same}

1 is a cross-sectional view illustrating a blank mask in which a light shielding film and an antireflection film are formed on a phase inversion film according to the present invention.

2A to 2B are cross-sectional views illustrating the increase in size of the undercut or inclination of the cross-sectional shape after fabrication of the photomask at the interface between the light shielding portion and the light transmitting portion.

3 is a cross-sectional view showing a blank mask in which an antireflection film formed of two layers of a first antireflection film and a second antireflection film is formed on a light shielding film.

4 is a cross-sectional view schematically showing a blank mask manufactured according to the first embodiment of the present invention.

5 is a graph schematically showing the reflectance of the blank mask manufactured by the first embodiment of the present invention.

6 is a cross-sectional view schematically showing a blank mask manufactured according to the second embodiment of the present invention.

7 is a graph schematically showing the reflectance of the blank mask produced by the second embodiment of the present invention.

<Overview of the main parts of the drawings>

1: transparent substrate 2: phase inversion film

3: shading film and anti-reflection film 4, 11: shading film

5, 24, 35: Photosensitive agent 6: Scum

12: Anti-reflection film 13: Resolution degradation area of the photomask pattern

21, 31: first antireflection film 22, 32: second antireflection film

23, 34: oxide film 33: third antireflection film

BACKGROUND In the manufacture of semiconductor integrated circuits and liquid crystal displays, lithographic methods are generally used to process fine patterns. In the lithography method, a photomask having a micropattern formed of a light transmitting portion that transmits light and a light blocking portion that blocks light is mounted on an exposure apparatus such as a stepper or a scanner, and reduced exposure using ultraviolet rays or the like to photoresist on a silicon wafer. A method of forming a micro pattern of a reduced shape having the same shape as a photomask by transferring the same to a photomask. At this time, the pattern is reduced by the lens of the exposure apparatus. When the reflectance of the photomask is high, the light reflected from the photomask interferes with the transmitted light or is reflected by the lens of the exposure apparatus, thereby degrading the precision of the pattern by multiple reflection. There was a problem. In particular, as the critical dimension of the pattern of the semiconductor integrated circuit is further miniaturized and highly integrated, a phase inversion photomask called a phase inversion mask has been developed and used. In particular, in the case of an attenuation type phase inversion mask (EAPSM), As shown in FIG. 1, the light shielding film and the anti-reflection film are formed on the phase inversion film so that the cross section after the photomask is manufactured in two stages, which causes a problem that the deterioration of the pattern accuracy due to multiple reflections is further increased. The phase inversion mask controls the intensity of light transmitted at the boundary between the light transmitting portion and the light blocking portion of the photomask to be 4 to 20%, and reverses the phase of the light by 180 degrees to cancel the light diffracted by passing through the light transmitting portion at the boundary of the light transmitting portion. As the intensity is reduced by the phenomenon, the resolution is prevented from being deteriorated due to constructive interference between the transmitted light and the adjacent transmitted light. Therefore, when the transmittance change and the phase change caused by the multiple reflections occur, the resolution decreases. do.

In order to improve the above problems, it is common to form an antireflection film in the blank mask step, which is a material of the photomask, to lower the reflectance of the blank mask and the photomask. However, in the conventional antireflection film, the reflectance of the antireflection film is increased due to the shortening of the exposure light due to the recent decrease in the minimum line width, so that the reflectance at the chromium fluoride (KrF) and argon fluoride (ArF) excimer laser exposure wavelengths is about 20%. There was a problem that the prevention effect is not sufficient. In addition, the conventional anti-reflection film has to be miniaturized in order to cope with the reduction in the minimum line width, for this purpose, the thickness of the photoresist, light shielding film and the anti-reflection film of the blank mask is reduced. However, when the thickness of the anti-reflection film of the blank mask is reduced, the reflectance is increased at 488 nm or 365 nm, which is a laser wavelength used in an inspection apparatus for inspecting defects or foreign substances of the photomask, thereby making it difficult to detect defects or foreign substances of the photomask. In addition, when the thickness of the anti-reflection film is increased to reduce the defect of the photomask or the reflectance at the foreign material inspection wavelength, the thickness of the film is increased, and as shown in FIGS. The size of the undercut or the slope increases at the interface between the and the light emitting portion. As a result, an increase in the resolution lowering area causes scattering of exposure light that is incident vertically during the lithography process, thereby lowering the resolution, which makes it difficult to cope with the reduction of the minimum line width.

In addition, the conventional anti-reflection film is formed in such a way that the cross-sectional shape of the interface between the light transmitting portion and the light blocking portion becomes undercut or inclined after manufacturing the photomask by wet and dry etching because the speed of wet and dry etching is different from that of the light blocking film. In the lithography process, the exposure light is scattered at the interface between the light transmitting portion and the light blocking portion, thereby reducing the resolution. In particular, as shown in FIG. 1, in the case of an attenuated phase inversion mask that forms a phase inversion pattern on the interface between the light blocking portion and the light transmitting portion, the light scattered from the interface between the light blocking portion and the light transmitting portion in the lithography process is applied to the phase inversion film. There was a problem that the resolution is reduced by affecting the phase inversion and transmittance.

In addition, conventionally, there is a problem that the flatness is increased by the internal stress of the anti-reflection film generated when the anti-reflection film is formed. If the flatness of the blank mask is increased, the photomask flatness is changed by the reduction of internal stress during the photomask manufacturing process, thereby shifting the position of the photomask pattern, thus adversely affecting the lithography process.

In addition, since the conventional antireflection film has a high ammonia concentration on the surface of the antireflection film, when the photomask pattern is exposed by coating a chemical amplification resist on the antireflection film, basic ammonia ions on the antireflection film surface are formed on the chemical amplification resist after exposure. By neutralizing the acidic hydrogen ions, an undeveloped scum is formed on the surface of the light transmitting portion. The generation of such scum has a problem that it is difficult to etch because it interferes with wet etching or dry etching, or it is difficult to control the size of the photomask pattern.

Anti-reflection film forming method of the blank mask of the present invention, as shown in Figure 3 to solve the problem of the anti-reflection film, is composed of two or more layers of the first anti-reflection film and the second anti-reflection film on the light shielding film By forming an anti-reflection film, there is provided a method of forming an anti-reflection film of a blank mask for a blank mask for binary and phase inversion photomasks having reduced reflectance at krypton fluoride (KrF) and argon fluoride (ArF) excimer laser exposure wavelengths. have.

In order to achieve the above object, the antireflection film composed of two or more layers was produced by appropriately adjusting the refractive index, thickness, and transmittance of each antireflection film so that the reflectance is reduced by the destructive interference at the exposure wavelength. In this case, the refractive index, thickness, and transmittance of the antireflection film composed of two or more layers are, as is generally known, (2 * refractive index * thickness) = (m-1/2) * (exposure), which is an offset interference condition of a thin film. Wavelength). Where m is 1, 2, 3. … Is an integer.

In addition, the antireflection film forming method of the blank mask of the present invention forms an antireflection film composed of two or more layers, whereby the reflectance at the photomask inspection wavelength is lower than that of forming the antireflection film with a single film having the same thickness. Accordingly, an object of the present invention is to provide a method of manufacturing a blank mask for binary and phase reversal photomasks, which facilitates inspection of defects and foreign substances.

In addition, the anti-reflection film forming method of the blank mask of the present invention, by forming an anti-reflection film composed of two or more layers of the metal compound of the same series, thereby simplifying the process when manufacturing the photomask and improved yield of the photomask An object of the present invention is to provide a method of manufacturing a blank mask for binary and phase reversal photomasks.

In addition, the anti-reflection film forming method of the blank mask of the present invention, so that the thickness of the anti-reflection film composed of two or more layers to minimize the binary line and phase reversal photo for manufacturing an advanced photomask that can cope with the minimum line width reduction It is an object to provide a method of manufacturing a blank mask for a mask.

In addition, the anti-reflection film forming method of the blank mask of the present invention, considering the thickness of the anti-reflection film composed of two or more layers, the transmittance at the exposure wavelength, the wet etching and the dry etching rate, the thickness and transmittance and the wet type of the light shielding film By appropriately adjusting the speed of etching and dry etching, the photomasks manufactured by wet etching and dry etching form vertical cross sections, and minimize the scattered light at the interface between the light transmitting part and the light blocking part to reduce the minimum line width. An object of the present invention is to provide a method of manufacturing a blank mask for binary and phase reversal photomasks for manufacturing a photomask having a minimum resolution reduction.

In addition, the antireflection film forming method of the blank mask of the present invention can further lower the reflectance by oxidizing, nitriding, carbonizing or fluorinating the surface of the antireflection film by performing heat treatment under high vacuum, medium vacuum, or atmospheric pressure under a controlled gas atmosphere. In addition, it is an object of the present invention to provide a method for manufacturing a blank mask for binary and phase reversal photomasks having low substrate flatness due to relaxation of internal stress due to thin film formation.

In addition, the anti-reflective film forming method of the blank mask of the present invention is a heat treatment under high vacuum, medium vacuum or atmospheric pressure under a controlled gas atmosphere to control the film properties of the surface in addition to the reduction of reflectance and substrate flatness, It can reduce the scum in the manufacture of photomasks using binary and phase-inverted blank masks coated with chemically amplified resist (CAR) by improving the adhesion of the ammonia (NH3). An object of the present invention is to provide a method of manufacturing a blank mask for binary and phase reversal photomasks.

In order to solve the above problems, an anti-reflection film, a light shielding film forming method, and a blank mask manufacturing method according to the present invention are as follows.

The antireflection film, the light shielding film formation method and the blank mask manufacturing method according to the present invention, after forming a light shielding film containing at least a metal and nitrogen on a transparent substrate to form a two or more multilayer thin film of an antireflection film containing at least a metal and oxygen. Or an anti-reflection film containing at least metal and oxygen on a transparent substrate as two or more multilayer thin films.

Configuration 1) The antireflection film, light shielding film formation method and blank mask manufacturing method according to the present invention are characterized in that the reflectance is maintained at 5 to 20% at any exposure wavelength of 150 to 400 nm.

Configuration 2) The antireflection film, light shielding film formation method and blank mask manufacturing method according to the present invention are characterized in that the reflectance is maintained at 5 to 50% at a wavelength of 200 to 700 nm.

Configuration 3) The antireflection film, the light shielding film formation method and the blank mask manufacturing method according to the present invention are characterized in that two or more multilayer thin films constituting the antireflection film are formed of the same series metal or metal compound.

Structure 5) The antireflection film, light shielding film formation method and blank mask manufacturing method according to the present invention are characterized in that the optical thickness (= refractive index * thickness) of each antireflection film is 5 to 100 nm at any exposure wavelength of 150 to 400 nm. It is done.

Structure 6) The antireflection film, light shielding film formation method and blank mask manufacturing method according to the present invention are characterized in that the total thickness of the film composed of the light shielding film, the antireflection film or the antireflection film is maintained at 300-1500 kPa.

Configuration 7) The antireflection film, the light shielding film formation method and the blank mask manufacturing method according to the present invention are characterized in that the resolution reduction area of the cross section is maintained at 1500 占 Å or less during the production of the photomask.

Constitution 8) The antireflection film, light shielding film formation method and blank mask manufacturing method according to the present invention are formed by physical vapor deposition (PVD) or chemical vapor deposition (CVD) and atomic layer deposition (ALD) in forming the light shielding film and the antireflection film. It can be formed, in particular, characterized by being formed by reactive sputtering.

9) The antireflection film, the light shielding film forming method and the blank mask manufacturing method according to the present invention do not use an atmosphere gas after the light shielding film and the antireflection film or the antireflection film are formed, or air, oxygen (O ₂ ), nitrogen (N ₂ ), carbon monoxide (CO), carbon dioxide (CO ₂ ), nitrous oxide (N ₂ O), nitrogen oxides (NO), nitrogen dioxide (NO ₂ ), ammonia (NH ₃ ), methane (CH ₄ ) and fluorine ( At least one of the metal oxide film, the metal nitride film, the metal carbide film, or the metal fluoride film from the surface by heat treatment at 100 to 500 ° C. under vacuum or atmospheric pressure in a gas atmosphere selected from the group consisting of F ₂ ). The thickness of the film thus formed is 1 to 15 nm.

Configuration 10) The antireflection film, light shielding film formation method and blank mask manufacturing method according to the present invention are characterized in that the flatness of the substrate is 500 nm or less by the heat treatment in the configuration 8).

Structure 11) The antireflection film, light shielding film formation method and blank mask production method according to the present invention are characterized in that the concentration of ammonia (NH 3) ions on the surface is 10 ppm or less by the heat treatment in the configuration 8).

Composition 12) The anti-reflection film, light-shielding film forming method and blank mask manufacturing method according to the present invention is the light-shielding film and the anti-reflection film is a material capable of forming a fine pattern by wet etching or dry etching or dry etching and wet etching, metal and oxygen, Characterized in that it is formed of a material containing at least one of nitrogen, carbon, fluorine.

Structure 13) The antireflection film, light shielding film formation method and blank mask manufacturing method according to the present invention are characterized in that the light shielding film and the antireflection film are formed of a material containing at least one of chromium, oxygen, nitrogen, carbon, and fluorine. do.

Structure 14) The antireflection film, the light shielding film formation method and the blank mask manufacturing method according to the present invention are formed by the method of the light shielding film and the antireflection film in the configuration 7), and includes oxygen (O ₂ ), nitrogen (N ₂ ), and carbon monoxide. (CO), carbon dioxide (CO ₂ ), nitrous oxide (N ₂ O), nitrogen oxides (NO), nitrogen dioxide (NO ₂ ), ammonia (NH ₃ ), methane (CH ₄ ) and fluorine (F ₂ ) It is characterized by using at least one or more selected from.

According to the present invention, the antireflection film composed of two or more layers is not limited to the composition of each film. That is, each antireflection film may be composed of a discontinuous antireflection film or a continuous antireflection film, and a form in which the discontinuous film and the continuous film are mixed may be possible.

According to the present invention, the light shielding film including metal and nitrogen includes 30 to 90 at% of metal, 10 to 70 at% of nitrogen, 40 to 80 at% of metal, 20 to 60 at% of nitrogen, and carbon. It is preferable that 0 to 20% is included. In addition, the anti-reflection film includes 30 to 70 at% of metal and 30 to 70 at% of oxygen, 30 to 70 at% of metal, 30 to 70 at% of oxygen, 0 to 40 at% of nitrogen, and 0 of carbon. It is preferable to include from 30 at%.

In addition, according to the present invention, the metal forming the anti-reflection film and the light shielding film should be a material capable of forming microcircuits by wet etching, dry etching, or wet etching and dry etching methods, and may include chromium (Cr) and cobalt (Co). ), Tantalum (Ta), tungsten (W), molybdenum (Mo), vanadium (V), palladium (Pd), titanium (Ti), niobium (Nb), hafnium (Hf), germanium (Ge), aluminum (Al ), Platinum (Pt), iron (Fe), silicon (Si) nickel (Ni), zirconium (Zr), indium tin oxide (ITO) can be selected at least one or more selected from the group consisting of, using chromium More preferably.

In addition, according to the present invention, in the manufacture of binary binary and phase inverted blank masks for semiconductors, two or more layers of antireflective films having appropriately adjusted refractive index, thickness, and transmittance may be used so that the reflectance of the light incident on the antireflective film may be lowered due to extinction interference. By forming a multilayer film, the reflectance at the exposure wavelength in the lithography process is 365 nm, the I-line wavelength of the mercury lamp, 248 nm, the fluoride krypton laser wavelength, 193 nm, the argon fluoride laser wavelength, or 157 nm, the F ₂ laser wavelength, and the photomask is further reduced. The reflectance at 257 nm, 365 nm, and 488 nm, which are inspection wavelengths of defects and foreign matters, can be maintained at 50% or less. Generally, it is known that the lower the reflectance of the antireflective film is, the better, but in this case, since a defect occurs in the blank mask along with the problem of the cross-sectional shape of the photomask, the reflectance at the exposure wavelength of the lithography process is preferably 5% to 20%. More preferably 8 to 15%. In addition, the reflectance at the lithography exposure wavelength is 25% or less, and the reflectance at 257 nm, 365 nm, and 488 nm, which are inspection wavelengths of defects and foreign substances of the photomask, is maintained at 50% or less, and the reflectance at the inspection wavelength is 40%. It is more preferable to be% or less.

Further, according to the method of the present invention, the optical thickness (refractive index * thickness) of each of the antireflective films can be formed to have the same thickness as the lithography wavelength from 1/40 to the lithography wavelength in order to maintain the reflectance caused by the destructive interference. It is preferable to set it as 1/20 to 1/2 of a wavelength. In addition, by forming a multilayer antireflection thin film having different refractive indices, it is possible to further reduce the reflectance in the visible light region as well as the lithography wavelength. At this time, it is more preferable that the thickness of the multilayer antireflective thin film be increased to two layers in consideration of productivity and productivity. In addition, the thickness of the light shielding film may be appropriately adjusted in consideration of the thickness of the antireflection film, and in some cases, the formation of the light shielding film may be omitted.

In addition, according to the method of the present invention, no atmospheric gas is used to further reduce the reflectance at the lithography wavelength, or the atmosphere, oxygen (O ₂ ), nitrogen (N ₂ ), carbon monoxide (CO), carbon dioxide (CO _2). ), At least one selected from the group consisting of nitrous oxide (N ₂ O), nitrogen oxides (NO), nitrogen dioxide (NO ₂ ), ammonia (NH ₃ ), methane (CH ₄ ) and fluorine (F ₂ ) Heat treatment at 100 to 800 ° C. under vacuum or atmospheric pressure to form an antireflection film surface containing at least one or more types from an oxide film, nitride film, carbide film, and fluoride film group. The heat treatment time is 0 to 60 minutes to form a thickness of 1 to 15nm. In addition, if the heat treatment temperature is too low, the effect of reducing the reflectance becomes smaller, so it is more preferable to set the heat treatment temperature to 200 ° C. or more. If the heat treatment temperature is too high, crystallization of the thin film proceeds and the mean square roughness (nmRMS) of the surface of the antireflection film is increased. Since becomes large, it is more preferable to make the heat processing temperature into 500 degrees C or less. At this time, the mean square roughness (nmRMS) of the antireflection film surface is adjusted to 0.1 to 5 nm by adjusting the heat treatment temperature and time.

In addition, according to the method of the present invention, the substrate is warped due to the multilayer thin film stress caused by the reactive sputtering method, thereby increasing the flatness. When the substrate flatness is increased, the pattern is distorted during the lithography process and transferred. Cause the pattern to bend. Therefore, the flatness after thin film formation should be adjusted so as not to become large, and it is preferable that the flatness after thin film formation and after fabrication of a photomask does not become 500 nm or more. In the present invention, in order to reduce the flatness, the atmosphere gas, temperature, and heat treatment time of the above-described structure 8) during heat treatment were appropriately adjusted.

In addition, according to the present invention, when the chemically amplified resist is coated on the antireflection film, the film close to the surface of the antireflection film should have very low adsorption of ammonia. The chemically amplified resist forms acidic hydrogen ions when the photomask is manufactured. The acidic hydrogen ions are neutralized by ammonia adsorbed on the surface of the anti-reflection film to form a scum as shown in FIG. 3 after exposure and development. In addition, since the scum interferes with wet etching and dry etching, it is difficult to manufacture a photomask. Therefore, the ammonia concentration on the surface of the antireflection film is preferably maintained at 10 ppm or less, more preferably 2 ppm or less. In order to prevent the antireflection film surface and the ammonia adsorption, ammonia on the antireflection film surface should be removed by the heat treatment method, and heat treatment in an atmosphere gas containing oxygen and vacuum is more preferable.

The heat treatment method of the configuration 8) is not limited to the heating method. That is, any method capable of heating the blank mask is possible, such as a lamp heater, heating using a hot wire, and heating using a laser.

In the present invention, the transparent substrate may use synthetic quartz glass and synthetic quartz glass coated with calcium fluoride (CaF 2) and magnesium fluoride (MgF 2), and may use any transparent substrate that transmits the exposure light of lithography. .

In the configuration 7), vapor deposition methods such as physical vapor deposition (PVD), chemical vapor deposition (CVD), and atomic layer deposition (ALD) are not limited. That is, inline type, cluster type, or batch type can be used, and it is also possible to use a mixture of deposition apparatuses and methods of different methods in any order.

According to the present invention, the antireflection film, the light shielding film formation method and the blank mask manufacturing method have a low reflectance at a lithography exposure wavelength, facilitate the pattern inspection of the photomask, minimize scum occurrence, and minimize the resolution degradation area. It is possible to manufacture a photomask. When the lithography process is performed using the above photomask, the decrease in the resolution due to multiple reflections is minimized because the reflectance at the exposure wavelength is low, and since the substrate flatness of the photomask is small, the distortion of the pattern is minimized so that the smallest minimum It can be used for line width production.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. While many specific details are set forth in order to provide a more general understanding of the invention, such as the following description and the annexed drawings, these specific details are illustrated for the purpose of illustrating the invention and are not meant to limit the invention thereto. And a detailed description of known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

Example 1

4 is a view for schematically explaining a blank mask manufactured according to the first embodiment of the present invention.

Referring to the drawings, in the blank mask according to the first embodiment of the present invention, a synthetic quartz glass substrate having a width of 6 inches by 6 inches and a thickness of 0.25 inches polished as a transparent substrate was used. The flatness of the synthetic quartz glass substrate was measured at 420 nm.

First, a phase reversal film was formed on the transparent substrate to a thickness of 70 nm by a reactive sputtering method using a sputtering device.

The light shielding film was then formed into a 40 nm thick chromium carbide nitride film (CrCN). The chromium carbide nitride film was formed by using argon gas as an inert gas, nitrogen and methane gas as a reactive gas, and applying an appropriately regulated power to a chromium target in a sputtering apparatus. At this time, the volume ratio of argon is 40 to 90%, the volume ratio of nitrogen is 5 to 40%, and the volume ratio of methane is 0 to 20% in order to control the transmittance and thickness of the light shielding film, the wet etching rate and the dry etching rate. It was formed by adjusting the power properly. The transmittance and thickness were adjusted so that the transmittance at the lithography exposure wavelength was 1% or less, and the rates of wet etching and dry etching were adjusted to be equal to or faster than the etching rate of the first antireflection film.

Then, a 7 nm thick chromium carbide nitride oxide film (CrCON) is formed as the first antireflection film on the light shielding film. The chromium carbide nitride oxide film was formed by using the above sputtering device, argon gas as an inert gas, injecting nitrogen, carbon dioxide and methane gas as a reactive gas, and then applying appropriately regulated power to the chromium target. At this time, in order to adjust the transmittance, refractive index, thickness, wet etching and dry etching rate of the first anti-reflection film, the volume ratio of argon is 40 to 95%, the volume ratio of nitrogen is 5 to 80%, and the volume ratio of carbon dioxide is 1 to 50. % And volume ratio of methane were 0-30%, and it formed by adjusting power suitably together. The first antireflection film of 7 nm was adjusted so that the transmittance was 60 to 90% at 193 nm wavelength and 70 to 95% at 248 nm wavelength, and the refractive index was lower than that of the light shielding film and higher than the second antireflection film. In addition, the speed of wet etching and dry etching was adjusted to be equal to or slower than that of the light shielding film.

Then, a chromium carbide nitride oxide film having a thickness of 8 nm is formed on the first antireflection film as a second antireflection film. The chromium carbide nitride oxide film was formed by injecting nitrogen, carbon dioxide, and methane gas with argon as an inert gas using the above sputtering device, and then applying an appropriately controlled electric power to the chromium target. At this time, to adjust the transmittance, refractive index, thickness, wet etching and dry etching rate of the second anti-reflection film, the volume ratio of argon is 40 to 95%, the volume ratio of nitrogen is 5 to 80%, and the volume ratio of carbon dioxide is 1 to 50. The volume ratio of% and methane was 0-30%, and it formed by adjusting power suitably with this. The second anti-reflection film having a thickness of 8 nm was adjusted to have a transmittance of 60 to 90% at a wavelength of 193 nm and 70 to 95% at a wavelength of 248 nm, and higher than the first anti-reflection film. In addition, the refractive index was adjusted to be lower than that of the light shielding film and the first anti-reflection film, and the speed of the wet etching and the dry etching was adjusted to be equal to or faster than the etching rate of the first anti-reflection film.

Then, the blank mask is placed in a vacuum chamber and heat-treated for the purpose of reducing the reflectance of the blank mask on which the phase inversion film, the light shielding film, the first antireflection film, and the second antireflection film are formed, reducing the flatness of the substrate, and removing ammonia from the surface. Do Atmospheric gas was used by appropriately adjusting the oxygen, heated by adjusting the infrared lamp heater to an appropriate temperature in a vacuum. At this time, the reflectance of the film prepared by the above method was measured by Varian's Cary400 measuring device, and the reflectance at 193nm wavelength was measured as 13% and reflectance at 248nm wavelength was 10%. The characteristic was obtained. 5 schematically shows the reflectance of the blank mask prepared by Example 1 of the present invention. In addition, reflectance was measured at 15% and 28%, respectively, at the wavelengths of 365 nm and 488 nm, which are commonly used inspection wavelengths, so there was no problem in inspecting defects and foreign objects in the manufacturing of photomasks. In order to analyze the components of the light shielding film, the first antireflection film, and the second antireflection film, the analysis was performed by AES analysis. As for the light shielding film, chromium was 52 at%, carbon at 27 at%, and nitrogen at 22 at%. 1 The antireflection film was measured to have 35 at% of chromium, 12 at carbon, 42 at% of oxygen, and 11 at% of nitrogen. The second antireflection film had 23 at% of chromium, 13 at% of carbon, and oxygen. Was measured at 48 at% and nitrogen at 16 at%. The surface treated by heat treatment was measured at 9 at% chromium, 35 at% carbon, 57 at% oxygen and 9 at% nitrogen. The depth of the film on which the oxide film was formed was measured at 2.1 nm. As a result of measuring the root mean square roughness (nmRMS) of the substrate by heat treatment with AFM (Atomic Force Microscope), it was measured as 0.8 nmRMS, so there was no problem that the roughness by heat treatment was increased. In addition, in order to measure the flatness of the substrate, the flatness of the substrate was measured at 370 nm as measured by the substrate flatness measuring equipment FM-200. In addition, in order to analyze the ammonia concentration, the surface was analyzed by ion chromatography (Ion Chromatography) method, the ammonia concentration was measured to 30ppb.

Next, a chemically amplified resist was coated on the phase inversion film, the light shielding film, the first antireflection film, and the second antireflection film by spin coating to produce a low reflection blank mask.

Then, the photomask was produced using the said low reflection blank mask. First, the pattern was exposed with an electron beam, and a post-exposure baking (PEB) process and a developing process were performed. At this time, the cross section of the photomask after exposure and development was cut and the cut surface was observed by SEM (Scanning Electron Microscope) measuring method to check whether scum was generated, and scum did not occur.

After that, the second anti-reflection film, the first anti-reflection film, and the light shielding film of the same metal were sequentially etched, and the phase inversion film was etched with different dry etching conditions.

Then, the second antireflection film, the first antireflection film, and the light shielding film were etched by wet etching, and a resist strip and a cleaning were performed to prepare a low reflection photomask.

The low reflection photomask manufactured according to the method of the present embodiment was formed with a precise pattern size, and the cut surface was observed by SEM measurement. As a result, the inclination of the undercut or pattern surface was very small, and the resolution reduction area was 10 to 10. Measured at 30 nm.

Example 2

6 is a view for schematically explaining a blank mask manufactured according to a second embodiment of the present invention.

Referring to the drawings, first, a phase inversion film having a thickness of 70 nm is formed on the transparent substrate by using the sputtering device. In this case, the flatness of the transparent substrate was measured at 380 nm.

Then, a 55 nm thick chromium carbide oxynitride film (CrCON) is formed on the phase inversion film as a first anti-reflection film by reactive sputtering. The chromium carbide nitride film was formed by injecting nitrogen, carbon dioxide gas, and methane gas as a reactive gas with argon, which is an inert gas, and then applying appropriately regulated power to the chromium target. At this time, the volume ratio of argon is 40 to 95%, the volume ratio of nitrogen is 5 to 80%, and the volume ratio of carbon dioxide is 1 to 50% in order to control the rate of transmittance, thickness, wet etching and dry etching of the first antireflection film. , The volume ratio of methane was 0 to 30%, and the power was properly adjusted. Since the first anti-reflection film simultaneously serves as a light shielding film together with the role of anti-reflection, the first anti-reflection film having a thickness of 55 nm was adjusted to have a transmittance of 1% or less at 193 nm and 248 nm wavelengths. In addition, the wet etching rate and the dry etching rate were adjusted to be equal to or faster than the etching rate of the second anti-reflection film.

Then, a 7 nm thick chromium carbide nitride oxide film (CrCON) is formed as a second antireflection film on the first antireflection film. The chromium carbide nitride oxide film is formed by using the above sputtering device, argon as an inert gas, injecting nitrogen, carbon dioxide and methane gas as a reactive gas with proper adjustment, and then applying appropriately regulated power to the chromium target. It became. At this time, to adjust the transmittance, thickness, wet etching and dry etching rate of the first anti-reflection film, the volume ratio of argon is 40 to 95%, the volume ratio of nitrogen is 5 to 80%, the volume ratio of carbon dioxide is 1 to 50%, The volume ratio of methane was 0-30%, and it formed by adjusting power suitably together. The second anti-reflection film having a thickness of 7 nm was adjusted so that the transmittance was 70 to 90% at 193 nm wavelength and 70 to 95% at 248 nm wavelength. In addition, the wet etching rate and the dry etching rate were adjusted to be equal to or slower than that of the first anti-reflection film.

Then, a chromium carbide nitride oxide film having a thickness of 8 nm is formed on the second antireflection film as a third antireflection film. The chromium carbide nitride oxide film was formed by injecting nitrogen, carbon dioxide, and methane gas with argon as an inert gas using the above sputtering device, and then applying a properly regulated voltage to the chromium target. At this time, in order to adjust the transmittance, thickness, wet etching and dry etching rate of the first anti-reflection film, the volume ratio of argon is 40 to 95%, the volume ratio of nitrogen is 5 to 80%, the volume ratio of carbon dioxide is 1 to 50%, The volume ratio of methane was 0-30%, and it formed by adjusting power suitably together. The third anti-reflection film having a thickness of 8 nm was adjusted such that the transmittance was 70 to 90% at a wavelength of 193 nm and 70 to 95% at a wavelength of 248 nm. In addition, the wet etching rate and the dry etching rate were adjusted to be equal to or slower than that of the second anti-reflection film.

The blank mask is then vacuum chambered for the purpose of reducing the reflectance of the blank mask having the phase inversion film, the first antireflection film, the second antireflection film, and the third antireflection film, reducing the flatness of the substrate, and removing ammonia from the surface. And heat treated. Atmospheric gas was used by appropriately adjusting the nitrogen oxide, heated by adjusting the infrared lamp heater to an appropriate temperature in a vacuum. At this time, the reflectance of the film prepared by the above method was measured by Varian's Cary400 measuring device, and the reflectance was measured at 11% at 193 nm and at 8% at 248 nm, resulting in a low reflection characteristic of 20% or less at the lithography exposure wavelength. Was obtained. 7 schematically shows the reflectance of the blank mask prepared by Example 2 of the present invention. In addition, the reflectances at 365 nm and 488 nm, which are commonly used inspection wavelengths, were measured at 12% and 20%, respectively, so that there were no problems in pattern defect and foreign material inspection during photomask fabrication. In addition, in order to measure the light shielding effect of the first antireflection film, the second antireflection film, and the third antireflection film, the transmittance at the lithography wavelength was measured by the Cary400 measuring device, and the transmittance at the 193 nm wavelength was 0.07% and 248 nm wavelength. The transmittance at was measured at 0.1%, so that there was no problem in acting as a light shielding film of the first antireflection film, the second antireflection film, and the third antireflection film. In addition, as a result of analyzing the components of the first anti-reflection film, the second anti-reflection film, and the third anti-reflection film by AES analysis, the first anti-reflection film was 42 at% chromium, 9 at% carbon and oxygen 27%, nitrogen was 22 at%, and the second antireflection film was measured at 35 at% chromium, 12 at carbon, 42 at% oxygen, 11 at% nitrogen, and at the third antireflection film. Chromium was measured at 20 at%, carbon at 11 at%, oxygen at 55 at%, and nitrogen at 14 at%. In the case of the surface by heat treatment, chromium was measured at 9 at%, carbon at 35 at%, oxygen at 57 at%, and nitrogen at 9 at%. The depth of the oxide film formed by the heat treatment was measured at 2.5 nm. When the root mean square roughness (nmRMS) of the substrate by heat treatment was measured by AFM (Atomic Force Microscope), it was measured by 0.9 nmRMS, and it was confirmed that there was no problem of increasing roughness by heat treatment. In addition, in order to measure the flatness of the substrate was measured by the substrate flatness measuring equipment FM-200, the flatness of the substrate was measured at 410nm. In addition, the surface was analyzed by ion chromatography (Ion Chromatography) method to analyze the ammonia concentration, the ammonia concentration was measured to 15ppb.

Then, a chemically amplified resist was coated on the phase inversion film, the first antireflection film, the second antireflection film, and the third antireflection film by spin coating to produce a low reflection blank mask.

Thereafter, the photomask process was performed in the same manner as in the first embodiment. At this time, the cross section of the photomask after exposure and development was cut and observed by observing the cut surface by SEM measurement method. As a result, scum did not occur. After fabrication of the low reflection photomask, the pattern size and position were formed accurately, and the occurrence of undercut on the cut surface was observed. Very small, the inclination of the pattern surface was very small, and the resolution reduction area was measured at 10 to 30 nm.

Effects according to the method of manufacturing the low reflection blank mask of the present invention are as follows.

First, when the lithography process is performed using a low reflection photomask manufactured using the low reflection blank mask of the present invention, the reflectance at the exposure wavelength is reduced, thereby reducing the possibility of resolution reduction due to multiple reflections. Degradation of the resolution of the phase inversion type photomask is significantly reduced.

Secondly, the defects of the photomask and the reflectance at the wavelength of the foreign material inspection are appropriately adjusted so that there is no problem of defects and foreign material inspection in manufacturing the photomask.

Third, the anti-reflection film composed of two or more layers is made of the same metal-based material, thereby reducing the cost and yield of the blank mask and improving the wet and dry etching at the same time. This has the advantage of simplifying the photomask manufacturing.

Fourth, the etching rate of the wet etching and the dry etching of the anti-reflection film is appropriately adjusted to produce a photomask having a minimum resolution reduction area of the photomask pattern after the wet etching and the dry etching.

Fifth, the reflectance can be further lowered by heat treatment after the anti-reflection film is formed, thereby further reducing the resolution reduction due to multiple reflections in the lithography process.

Sixth, the flatness of the substrate is reduced by the effect of reducing the internal stress of the light shielding film and the anti-reflection film by heat treatment, and there is no change in the flatness during the photomask manufacturing process, so that the position of the photomask pattern is formed very accurately. A mask can be manufactured.

Seventh, by removing the ammonia on the surface by heat treatment to coat the chemically amplified resist on the anti-reflection film to minimize the occurrence of scum when manufacturing a photomask, there is no problem of wet etching and dry etching due to scum generation pattern size It is possible to manufacture a photomask formed accurately.

Claims (15)

A blank mask comprising a phase inversion film and a light shielding film mainly composed of a metal or a metal compound on a transparent substrate, A discontinuous multilayer of two or more layers composed of a metal series having a phase inversion film formed on the transparent substrate, an antireflection film formed on the phase inversion film, an antireflection film formed on the light shielding film, or an antireflection film formed on a transparent substrate A method of manufacturing a blank mask, characterized by forming a thin film or a continuous multilayer thin film or a discontinuous film and a continuous film. A blank mask comprising a phase inversion film and a light shielding film mainly composed of a metal or a metal compound on a transparent substrate, Each film constituting at least one antireflection film on the transparent substrate is composed of two or more discontinuous multilayer thin films composed of the same metal series, or a continuous multilayer thin film, or a mixture of discontinuous films and continuous films, wherein the antireflection film is formed of a light shielding film. Method for producing a blank mask, characterized in that to play a role at the same time. The method according to claim 1 or 2, Wherein each film constituting said at least one antireflection film has an optical thickness of 5 to 200 nm at an exposure wavelength of 150 to 400 nm. The method according to claim 1 or 2, Wherein each film constituting said at least one anti-reflection film is maintained at a reflectance of 5 to 20% at an exposure wavelength of 150 to 400 nm. The method according to claim 1 or 2, A method of manufacturing a blank mask, wherein each film constituting the at least one antireflection film has a reflectance of 5 to 50% at a wavelength of 200 to 700 nm. The method according to claim 1 or 2, The thickness of the light shielding film and the anti-reflection film or the thickness of the anti-reflection film is maintained at 30 to 150nm, the manufacturing method of the blank mask. The method according to claim 1 or 2, And the light shielding film and the anti-reflection film are formed by physical vapor deposition (PVD), chemical vapor deposition (CVD), or atomic layer deposition (ALD). The method according to claim 1 or 2, The light blocking film and the antireflection film may include cobalt (Co), tantalum (Ta), tungsten (W), molybdenum (Mo), chromium (Cr), vanadium (V), palladium (Pd), titanium (Ti), and niobium (Nb). , Zinc (Zn), hafnium (Hf), germanium (Ge), aluminum (Al), platinum (Pt), manganese (Mn), iron (Fe), silicon (Si) nickel (Ni), cadmium (Cd), At least one of zirconium (Zr), magnesium (Mg), lithium (Li), selenium (Se), copper (Cu), yttrium (Y), sulfur (S), indium tin oxide (InSnO), or a compound thereof And forming a material containing at least one material from the group consisting of oxygen (O), nitrogen (N), carbon (C) and fluorine (F). The method according to claim 1 or 2, The light shielding film and the antireflection film are made of chromium (Cr), and characterized in that the chromium compound containing at least one member from the group consisting of oxygen (O), nitrogen (N), carbon (C), fluorine (F). The manufacturing method of the blank mask made into. The method according to claim 1 or 2, The light shielding film and the antireflection film are formed by a reactive sputtering method, and together with an inert gas, oxygen (O ₂ ), nitrogen (N ₂ ), carbon monoxide (CO), carbon dioxide (CO ₂ ), and nitrous oxide (N ₂ ) as an atmosphere gas. A blank mask comprising at least one member from the group consisting of O), nitric oxide (NO), nitrogen dioxide (NO ₂ ), ammonia (NH ₃ ), methane (CH ₄ ) and fluorine (F ₂ ) . The method according to claim 1 or 2, The anti-reflection film is a blank mask, characterized in that the metal is composed of 20 to 60%, oxygen 40 to 80%. The method according to any one of claims 1 to 11, No atmosphere gas or air, oxygen (O ₂ ), nitrogen (N ₂ ), carbon monoxide (CO), carbon dioxide (CO ₂ ), nitrous oxide (N ₂ O), nitrogen oxides (NO), At least one or more selected from the group consisting of nitrogen dioxide (NO ₂ ), ammonia (NH ₃ ), methane (CH ₄ ) and fluorine (F ₂ ) is heat-treated at 100 to 500 ° C. under vacuum or atmospheric pressure to remove from the surface. A film containing at least one of a metal oxide film, a metal nitride film, a metal carbide film, or a metal fluoride film, The metal oxide film, the metal nitride film, the metal carbide film, or the metal fluoride film is formed with a thickness of 1 to 15nm, the manufacturing method of the blank mask. The method of claim 12, The flatness of a board | substrate becomes 500 nm or less by the said heat processing, The manufacturing method of the blank mask characterized by the above-mentioned. The method of claim 12, And the concentration of ammonia ions on the surface is 10 ppm or less by the heat treatment. The method according to any one of claims 1 to 14. The photomask is manufactured by using a binary blank mask or a phase inversion blank mask manufactured by the manufacturing method.

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