KR101197250B1 - Blankmask, Photomask and manutacturing method of the same - Google Patents

Abstract

Blank masks, photo masks and methods of making the same are disclosed. The blank mask is formed by sequentially laminating a transparent substrate, a metal film, a hard mask film, and a resist film. Here, at least one of the metal film and the hard mask film has a component change section in which the composition ratio of at least one element of the elements constituting the film is continuously changed in the depth direction of the film, and the composition ratio uniformity is 10% in the width direction of the metal film. Is less than or equal to According to the present invention, the optical density uniformity, the reflectance uniformity, the surface roughness, the chemical resistance, the exposure resistance, etc. can be improved when compared with a thin film having a uniform composition ratio of elements in the existing depth direction. The problem of stress can be reduced.

Description

Blank mask, photo mask and manufacturing method thereof {Blankmask, Photomask and manutacturing method of the same}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blank mask, a photo mask, and a method for manufacturing the same, which can implement a high precision minimum dimension (CD) in a semiconductor lithography process. A blank mask, a photo mask, and a method for manufacturing the same, which are applicable to ArF (wavelength: 193 nm) lithography, ArF immersion lithography capable of realizing a minimum line width.

In order to meet the demand for miniaturization of circuit patterns due to the high integration of large scale integrated circuits, advanced semiconductor microprocessing technology is becoming a very important factor. In the case of highly integrated circuits, circuit wiring is becoming finer for low power and high speed operation, and technical requirements for contact hole patterns for interlayer connection and circuit arrangement arrangement due to integration are increasing. Therefore, in order to meet these demands, there is a need for a technique capable of miniaturization in manufacturing a photomask in which an original of a circuit pattern is recorded and capable of recording a precise circuit pattern.

In particular, in order to form an ultra-precision circuit pattern of 65 nm or less, in recent years, a blank is used to etch a metal film forming a final pattern using an inorganic hard mask film as an etching mask without using an existing resist film as an etching mask. Mask structures are being developed. In the blank mask for the hard mask, the hard mask layer replaces the existing thick resist layer, and the hard mask layer may improve the aspect ratio and selectivity of the lower metal layer. Therefore, the loading effect during dry etching of the metal film is reduced, thereby obtaining excellent CD Mean to Target (MTT), CD linearity, CD uniformity, and the like.

Meanwhile, a conventional blank mask for a hard mask generally has a structure in which a light shielding film, a metal film, a hard mask film, and a resist film having a uniform composition ratio in the depth direction are sequentially formed on a 6025 size synthetic quartz glass substrate. In this case, the metal film may include an anti-reflection film, and the hard mask film functions as an etching mask. In this case, the uniformity of the composition ratio of the thin film in the depth direction means that the overall composition such as sputter target, process time, power, pressure, reactive gas, and inert gas type and input amount during thin film formation It means that the process conditions and the process environment are formed in the same state.

The thin film process in which the composition ratio is formed uniformly and stepwise in the depth direction has the advantage that each layer can play its role independently because the process change only changes in each step. For example, a light shielding film requires only two steps of process conditions, with a function of shielding exposure light having a specific wavelength, and an anti-reflection film reducing a surface reflectance with respect to the exposure light. There is an advantage that the metal film of the film is formed.

On the other hand, as the circuit pattern to be realized becomes more and more minutely, such as 65 nm or less, especially 45 nm or less, the uniformity, chemical resistance, surface roughness, residual stress, and growth defects of the thin film, in addition to the light blocking function and the antireflection function for exposure light The requirements for problems such as CD, CD uniformity and defects are becoming more stringent. This is a big problem when the above pattern is realized when the pattern is over 65 nm compared with the CD to be implemented, and the wavelength of the exposure light is relatively long, such as 365 nm i-line and 248 nm KrF. Did not occur. However, when forming ultra-precision patterns using short wavelengths such as 193 nm ArF for CD implementation of 65 nm or less, the residual stress, uniformity and thin film density of the existing thin films formed stepwise as the CD to be realized becomes finer. The defect which arises by this is becoming more serious problem.

However, when the above-described complex problems are solved by using a thin film formed in stages, it is difficult to solve the above problems due to a sudden change in composition ratio, thin film density, and residual stress that occur at the interface of the thin film. In order to satisfy density uniformity, reflectivity uniformity, chemical resistance, surface roughness, and growth defect characteristics, a complicated manufacturing process that requires the deposition of another thin film occurs. This complex process not only causes defects such as particles, but also increases the overall thickness of the thin film to increase the loading effect, resulting in a problem of lowering resolution, CD MTT, and CD uniformity. do.

The technical problem to be achieved by the present invention, the uniformity of reflectance, uniformity of optical density, adhesion between the thin film (Adhesion), residual stress (Growth Defect), chemical resistance (Chemical Durability), exposure durability (Exposure Durability) And binary blank masks, phase inversion blank masks, and hard masks for hard masks, which are used in ArF lithography and ArF immersion lithography with good thin film properties such as surface roughness.

In order to solve the above technical problem, a preferred embodiment of the blank mask according to the present invention is a transparent substrate, a metal film, a hard mask film and a resist film are sequentially stacked, at least one of the metal film and the hard mask film, The composition ratio of at least one element of the constituent elements includes a component change section that is a section in which the composition ratio is continuously changed in the depth direction of the film, and the composition ratio uniformity is less than or equal to 10% in the width direction of the metal film.

In order to solve the above other technical problem, a preferred embodiment of the photomask according to the present invention is a transparent substrate, a metal film, a hard mask film and a resist film are sequentially stacked, at least one of the metal film and the hard mask film And patterning and etching a blank mask including a component change section in which a composition ratio of at least one of the elements constituting the film is a section in which the composition ratio is continuously changed in the depth direction of the film, and the composition ratio uniformity is less than or equal to 10% in the width direction of the metal film. It is manufactured by.

In order to solve the above another technical problem, a preferred first embodiment of the blank mask manufacturing method according to the present invention (a) composition ratio uniformity in the width direction on the transparent substrate while maintaining the same process conditions for the first deposition time Depositing a metal film such that is less than or equal to 10%; And (b) a composition ratio of at least one of the elements constituting the metal film by changing at least one of the plurality of process conditions constituting the process conditions applied during the second deposition time in a state where the plasma is turned on. Forming a component change section that is a section continuously changing in the depth direction of the film, wherein steps (a) and (b) are performed by changing the order or alternately.

In order to solve the above another technical problem, the second preferred embodiment of the blank mask manufacturing method according to the present invention is (a) the composition ratio uniformity is less than 10% in the width direction on the transparent substrate during the first deposition time or Depositing a metal film to be equal; And (b) changing at least one of the plurality of process conditions constituting the process conditions applied during the second deposition time in a state where the plasma is turned on, stepwise or continuously to form at least one of the elements constituting the hard mask film. And forming a component change section which is a section in which the composition ratio is continuously changed in the depth direction of the film.

According to the blank mask, the photo mask and the manufacturing method thereof according to the present invention, the blank mask is selectively changed continuously in the depth direction of the thin film with respect to at least one or more element contents constituting the thin film at the time of manufacture so that the adhesive force, reflectance uniformity, It can improve the chemical resistance and residual stress characteristics. In addition, according to the present invention, it is possible to manufacture a blank mask having excellent characteristics, through which a photo mask having excellent performance is possible.

1 is a cross-sectional view of a preferred embodiment of a blank mask for a hard mask according to the present invention;
2 is a flowchart illustrating a process of performing a preferred embodiment of the blank mask manufacturing method for a hard mask according to the present invention;
3 is a schematic diagram of a long through sputtering equipment used in the manufacture of a blank mask for a hard mask according to the present invention, and
Figure 4 is a graph showing the composition ratio analysis results of the thin film according to the embodiment of the blank for the hard mask according to the present invention.

Hereinafter, exemplary embodiments of a blank mask, a photo mask, and a method of manufacturing the same according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a cross-sectional view of a blank mask for a hard mask according to the present invention.

Referring to FIG. 1, the blank mask 100 for a hard mask according to the present invention includes a transparent substrate 110, a metal film 120, a hard mask film 130, and a resist film 140. The transparent substrate 110, the metal film 120, the hard mask film 130, and the resist film 140 are sequentially stacked. In this case, at least one of the metal film 120 and the hard mask film 130 is a section in which the composition ratio of at least one of the elements constituting the film varies within a range of 1 to 50 at% (hereinafter, referred to as a 'component change section'). ).

In addition, the section in which the composition ratio of at least one element among the elements constituting the film is continuously changed in the depth direction of the film is formed to mean a section in which the process conditions for controlling the characteristics of each thin film are continuously or stepwise changed without turning off the plasma. It is meant to include one or more deposited. That is, in order to form a section continuously changing in the depth direction of the film, it means that the process conditions are continuously or stepwise changed during the sputtering of the thin film on the substrate.

The transparent substrate 110 is formed by performing a plurality of lapping processes and polishing processes on the substrate base material. The material of the transparent substrate 110 may be one of synthetic quartz, calcium fluoride (CaF 2), and fluorine-doped quartz. The size of the transparent substrate 110 is 6025, and the birefringence at 193 nm is preferably 2 nm / 6.35 mm or less. At this time, the substrate base material is made of silicon oxide (SiO ₂ ) with a purity of 99.9999% or more, and the synthetic quartz ingot is manufactured through slicing and edge grinding process, and has a size of 152x152 ± 0.2 mm and 6.3 mm. It has more than thickness.

The transparent substrate 110 is manufactured by performing a plurality of lapping processes and a plurality of polishing processes on the substrate base material. First, a plurality of lapping processes are first performed on a substrate base material having a size of 152 × 152 ± 0.2 mm and a thickness of 6.3 mm or more. In the case of one lapping process, the lapping process is performed under high pressure using relatively large abrasive particles in consideration of the efficiency of the process. In this case, the target thickness reduction can be easily achieved, but damage occurs including cracks generated in the depth direction at the substrate surface. As such, cracks generated internally in the substrate base material are found as defects in a later process. In addition, the influence of coarse abrasive particles makes it difficult to achieve the target thickness accuracy. Therefore, the transparent substrate 110 used in the present invention is preferably manufactured by performing a plurality of lapping processes to achieve defect reduction and target thickness accuracy for the substrate base material. The abrasive grains applied in the lapping process of the substrate base material are at least one abrasive grain selected from silicon carbide (SiC), diamond (C), zirconia (ZrO ₂ ), and alumina (Al ₂ O ₃ ). Apply. In addition, the size of the abrasive particles applied to the lapping process is preferably 4 to 20 ㎛. If the size of the abrasive grain is 4 µm or less, the target thickness accuracy can be easily achieved, but the productivity decreases as the processing time becomes longer. And if the size of the abrasive grains is 20 µm or more, it is difficult to achieve the target thickness accuracy, and the defect level is lowered.

Next, a plurality of polishing processes are performed on the substrate base material on which a plurality of lapping processes are performed. The slurry used in such a plurality of polishing processes contains cerium oxide (CeO ₂ ), colloidal silica (SiO ₂ ) abrasive particles, hydrogen peroxide (H ₂ O ₂ ), nitric acid (HNO ₃ ) or potassium hydroxide (KOH) To adjust the pH. The overall pH of the polishing slurry in the polishing process is preferably adjusted to 6-12. In particular, an inorganic alkali such as potassium hydroxide (KOH) has the advantage of showing a synergistic effect by having an etching effect of the substrate base material. Meanwhile, in the polishing process, the abrasive particles physically remove the substrate base material. In this case, when the size of the abrasive grains is 5 μm or more, it is easy to achieve the target thickness reduction amount, but it may result in difficulty in obtaining good surface roughness. In addition, when the size of the abrasive grains is 0.5 μm or less, the thickness reduction amount of the substrate base material that has undergone the lapping process is small, requiring a long process time, thereby decreasing the efficiency of the process. Therefore, the size of the cerium oxide abrasive particles in the polishing process is preferably 0.5 to 5 ㎛. In addition, the size of the colloidal silica abrasive grains used in a plurality of polishing processes is preferably 20 to 200 nm. At this time, if the size of the colloidal silica abrasive particles is 20 nm or less, the efficiency of the polishing process is lowered, if it is 200 nm or more can not satisfy the surface roughness to be obtained in the polishing process.

Since the polishing process improves the surface roughness, it is preferable to gradually use small abrasive particles every time the polishing process is performed. Since the primary polishing process has a relatively rough surface due to the lapping process, it is necessary to remove a larger amount of substrate base material than the secondary and tertiary polishing processes. Therefore, in the primary polishing process, it is preferable to use a porous pad having high hardness and low compressibility as the polishing pad, and to use the soft pads SUBA # 400 to 800 in the secondary polishing process. At this time, the polishing pad determines the removal amount and the surface state of the substrate base material according to the type. The use of polishing pads below # 400 results in lower processing efficiency due to relatively high compression rate, elastic recovery rate and low hardness. When the polishing pad of # 800 or more is used, it is difficult to achieve the target surface roughness because of the low compressibility, elastic recovery rate and high hardness. In addition, it is preferable that the compressibility of the soft pad used in the secondary polishing process is 3% or more, and the elastic recovery rate is 65% or more. The polishing pad having a compression ratio of 3% or more elastically deforms the nap layer surrounding the particles when the polishing pressure is applied to the silica particles, thereby dispersing and absorbing the polishing pressure to suppress the formation of concave defects that may occur on the substrate surface. do. On the other hand, the polishing pad having a high elastic recovery rate of 65% or more can easily compress and recover the nap layer, so that large silica particles do not remain in the nap layer, thereby reducing concave defects. In the third polishing process, a suede pad, which is a super soft pad, is used as a polishing pad. Since the tertiary polishing process improves the surface roughness and particle characteristics as much as possible, ultra-soft polishing pads having low hardness, relatively high elastic recovery rate, and high compression rate are used. The ultra-soft polishing pad used in the tertiary polishing process is preferably 6% or more in compression rate and 72% or more in elastic recovery rate. Since the third polishing process requires more stringent control of defects, polishing pads having a higher compressibility and elastic recovery rate than secondary polishing pads should be used.

Grooves present in the polishing pad used in the polishing process may have various shapes. For example, a polishing pad having grooves having a pitch of 25 mm, a width of 4 mm, and a depth of 0.5 mm may be used. The groove of the polishing pad supplies a sufficient amount of slurry to the transparent substrate 110 during the polishing process, thereby increasing the polishing efficiency of the transparent substrate 110. At this time, it is also possible to use a polishing pad in which no groove is formed. The size of the grooves can be changed according to the polishing process, and whether or not the polishing pad in which the grooves are formed can be selectively determined according to the polishing process. Furthermore, in the case where the polishing pad used in the polishing step is composed of two or more layers, the thickness of the nap layer of the polishing pad corresponding to the two layers from the surface direction is preferably 200 to 600 µm. If the thickness of the nap layer is 200 μm or less, the elastic recovery rate of the polishing pad is reduced, making it difficult to secure surface roughness and adversely affecting defects including particles. If the nap layer is 600 μm or more, the efficiency of polishing for securing the surface roughness is low.

The metal film 120 is formed on the transparent substrate 110, and may be formed in a single layer or multiple layers, and at least one elemental composition ratio constituting the thin film at each inside or interface of each single layer or multilayer is continuously changed in the depth direction. It includes a continuous film. At this time, a continuous film is formed in which the ratio of at least one elemental component formed at least in the inside or the interface of the metal film 120 varies within a range of 1 to 50 at%, and the thickness of the continuous film is preferably greater than or equal to 50 GPa. In addition, when the metal film 120 is formed of a multilayer film including one or more different elements, a continuous film having a thickness of 5 nm or more may be positioned at an interface between a plurality of thin films constituting the metal film 120. The metal film 120 mentioned in the present specification is a thin film laminated from the surface on which the final pattern is formed to the transparent substrate 110, and is a portion below the final pattern such as an etch stop film, a stress reducing film, a light shielding film, and an antireflection film. All thin films of are referred to collectively. In addition, a phase inversion film may be selectively formed between the transparent substrate 110 and the metal film 120. The blank mask in which the phase inversion film is formed is called a halftone type phase inversion blank mask.

In addition, the composition ratio of nitrogen and / or silicon among the element composition ratios of the element elements constituting the metal film 120 has a continuous change, and the changing thickness is preferably 1 nm or more. Nitrogen acts as a factor affecting not only optical properties such as transmittance and reflectance of the thin film but also chemical resistance and exposure resistance. For example, when the content of nitrogen is high, the reflectance on the surface of the thin film is low in view of the optical properties of the thin film, while the content of nitrogen is low and the reflectance on the surface of the thin film is high. In addition, nitrogen also affects chemical resistance properties. As the nitrogen content increases, the chemical resistance properties of SC-1 and sulfuric acid deteriorate on the thin film surface, and the nitrogen content decreases the SC- on the thin film surface. 1 and excellent chemical resistance properties to sulfuric acid. Therefore, in order to consider such characteristics, it is preferable that the nitrogen content is designed to have different distributions in the film in the depth direction even when the metal film 120 is formed. In this case, if the change thickness is less than 1 nm, it is difficult to obtain a meaningful change result on the characteristics of the thin film as described above. Therefore, at least one section having a thickness of 1 nm or more is present in the section in which the nitrogen content continuously changes. desirable.

On the other hand, in the metal film 120 essentially including silicon, it is preferable that at least one section having a thickness of 5 nm or more in a continuous change section of the elemental composition ratio of silicon exists. In addition, in the blank mask for the hard mask, it is important to reduce the thickness of the metal film 120 and to select a material having excellent chemical resistance properties in order to reduce the loading effect. In this case, the content of silicon in the metal film 120 affects the optical and chemical resistance properties. As the ratio of the silicon composition ratio is higher, the transmittance is increased and the chemical resistance property is excellent. At this time, since the chemical resistance is obtained by evaluating the characteristics of the chemical on the surface of the metal film 120, the silicon content on the surface should be high. On the other hand, when the silicon content is higher than the thin film of the same thickness, the transmittance is high, and eventually the thickness of the thin film increases. Therefore, in order to satisfactorily satisfy the above characteristics, a section in which the content of the silicon composition ratio continuously changes in the depth direction of the film is essentially necessary, and the thickness of the section continuously changing in the depth direction of the metal film 120 is 5 nm. It is preferable that it is more than (more preferably, 10 nm or more).

Furthermore, the metal film 120 has a uniform composition ratio distribution in the width direction, in particular, the composition ratio uniformity in the width direction of the metal film 120 is 10% or less, and the density change in the depth direction of the thin film in the metal film 120 is 0.2. It is preferable that it is from 2.0 g / cm ³ . At this time, the composition ratio uniformity can be calculated by the following equation, and the measurement position is at least five places in the width direction. The composition ratio of the thin film can be analyzed by methods such as AES, XPS, and RBS.

On the other hand, if the density change in the depth direction of the thin film is less than 0.2 g / cm ^3, the another of the inner case is in analogy to the state, the density of the film unchanged is insignificant, and is greater than 2.0 g / cm ³ the effect is a thin film stress There is a big problem. In addition, the metal film 120 may have a different residual stress in the depth direction of the film, and may include a section having a difference in residual stress of 10 MPa or more. In this case, the metal film 120 includes a component change section in which a composition ratio of at least one or more elements is continuously changed in the depth direction of the film, and particularly, carbon may be selectively included to reduce residual stress in the thin film.

 Furthermore, the surface roughness can be controlled to 1.0 nmRa or less by including a component change section in which the composition ratio of the element changes in the surface portion of the metal film 120. The surface roughness of the metal film 120 is determined by the surface roughness state of the substrate, the kind of the sputtered atom, the reactive gas, and other process conditions. At this time, at least one of the type of reactive gas, deposition power, pressure in the chamber, and flow rate of the gas introduced into the chamber while the plasma is turned on may be continuously or stepwise changed to form a metal film on or inside the metal film 120. The surface roughness can be controlled by forming a component change section in which the composition ratio of at least one element among the elements constituting 120 is continuously changed in the depth direction of the film. In addition, it is preferable that the ratio of nitrogen atoms to depth relatively is high in the surface portion of the metal film 120. Furthermore, the metal film 120 preferably has an element ratio of nitrogen higher than the oxygen element ratio within a thickness range of 5 nm in the depth direction from the surface. In this case, it is particularly preferable that the nitrogen content of the outermost surface is distributed relatively high in the depth direction so that the reflectivity uniformity at 193 nm is within 1%.

In addition, when the metal film 120 has a multi-layered film structure in which one or more different elements are changed, an interface between thin films in which one or more of the same elements included in the thin films constituting the metal film 120 are in contact with each other. It is preferably formed continuously with a composition ratio change of 1 at% to 50 at% with a thickness of at least 5 nm. In the blank mask for the hard mask, the metal film 120 is a film exposed to the surface after the final patterning. At this time, in the case of a metal film having a uniform composition ratio of elements, the light shielding film for shielding light and the antireflection film for reducing the reflection of light are at least included. Residual stress is greatly generated. In addition, when the element composition of the interface (light shielding film and the anti-reflection film) of the thin film formed in steps is different from each other, a change in the thin film density occurs and a necking problem occurs as the etching ratio rapidly changes during dry etching. The necking was not a problem when the wafer was exposed because the CD error caused by the necking was insignificant compared to the pattern CD to be implemented in the CD of 65 nm or more, but when the CD was implemented in the nm or less of 65 nm, this resulted in a defect. .

In the present invention, by forming a component change section on the surface or inside of the thin film can reduce the problems caused by the rapid change in composition ratio and the thin film density change by the interface of the thin film. In this case, when the ratio of the elements forming the thin film is less than 1 at%, the change in the thin film stress and the dry etch ratio is reduced as compared with the conventional step-formed thin film. On the other hand, if the rate of change of the elements forming the thin film is 50 at% or more, the residual stress between the materials is suddenly changed, the same problem occurs as the thin film formed step by step. Therefore, the rate of change of one or more element components among the elements constituting the metal film 120 within the metal film 120 is within 1 at% to 50 at% (more preferably within 3 at% to 30 at%). It is preferable to form at least one layer of a continuous film.

Furthermore, the necking and the stress occur more as the size of the pattern to be realized becomes smaller. Therefore, in order to solve this problem, by forming a component change section when forming the metal film 120, it is possible to alleviate the problem of defects caused by necking and stress. Furthermore, properties such as chemical resistance, stress, and thin film density can be changed, whereby a blank mask having excellent thin film properties can be manufactured.

On the other hand, the metal film 120 is preferably faster than the change in the etching rate in the depth direction compared to the surface portion in at least one or more sections. In order to reduce the loading effect generated during the dry etching of the metal film 120, the etching ratio may increase in the depth direction of the thin film. This is because the thickness of the thin film exists in the depth direction, so that the metal film etched with radical ions becomes less reactive toward the depth direction. Therefore, in order to form a vertical pattern, it is preferable that the etching ratio increases toward the depth direction. In order to control the etching ratio, the etching ratio may be controlled to be fast or late by controlling the element ratio of nitrogen (N), oxygen (O), and carbon (C) when forming the continuous film.

Optical, physical, and chemical properties such as the thickness, optical density, chemical resistance, residual stress, and flatness of the metal film 120 including the continuous film as described above are described in the following table.

characteristic value Thickness of metal film 300 to 600 Å Optical density at the surface Within 2.7 to 3.5 for exposure light at 193 nm wavelength Chemical resistance After 1 hour of immersion in SC-1 (ammonia: hydrogen peroxide: ultra pure water = 1: 1: 5), the change in reflectance for exposure light at 193 nm is within 1%. Residual stress Within 100 MPa flatness Within ± 0.5 um

Meanwhile, the metal film 120 of the blank mask 100 according to the present invention may be formed by sputtering. In this case, the sputter target used to form the metal film 120 may include molybdenum silicide (MoSi), molybdenum tantalum silicide (MoTaSi), chromium (Cr), tantalum (Ta), tungsten (W), and silicon ( Si), molybdenum (Mo), titanium (Ti), ruthenium (Ru) and at least one element selected from. In the case of using a molybdenum silicide (MoSi) target, a target having a composition ratio of Mo: Si = 20 at%: 80at% and Mo: Si = 10 at%: 90 at% can be used. In addition, when the metal film 120 is formed step by step including a continuous film section, the MoSi sputter target for forming a portion of the metal film 120 adjacent to the substrate contains 10 to 30 at% of Mo, and the metal film The MoSi sputter target for forming the surface of 120 preferably contains 10 at% or less of Mo. Further, the metal film 120 may be deposited using DC reactive magnetron sputtering, RF reactive magnetron sputtering, long throw sputtering (LTS), or ion beam sputtering. In this sputtering, one or a mixture thereof selected from the group consisting of argon (Ar), helium (He), neon (Ne), and xenon (Xe) may be used as the inert gas. Reactive gases include oxygen (O ₂ ), nitrogen (N ₂ ), carbon monoxide (CO), carbon dioxide (CO ₂ ), nitrogen dioxide (NO ₂ ), nitrogen monoxide (NO), nitrous oxide (N ₂ O), ammonia (NH ₃ ) and one or a mixture thereof selected from the group consisting of methane (CH ₄ ) can be used.

In addition, when forming the metal film 120 by the sputtering process, it is preferable to proceed with the process while maintaining the distance between the substrate and the target 100 mm or more under a process pressure in the range of 0.1 to 0.15 Pa. And it is preferable to set the power density of a sputtering process to 0.6-13 W / mm, and to set board | substrate heating temperature to 50-300 degree | times. The substrate temperature in the sputtering process affects the adhesion force when the sputtered atoms collide with the substrate. Therefore, the adhesion between the substrate and the atoms can be enhanced by heating the substrate before sputtering, and in the case of a multilayer film, the adhesion between the thin film and the thin film is also increased. However, if the heating temperature is less than 50 degrees, the temperature is low, so that the effect of adhesion between the substrate and the thin film, the thin film and the thin film is insignificant, and when the heating temperature is more than 300 degrees, the flatness is deteriorated due to high residual stress during and after film formation. To have. Therefore, the substrate is preferably heated in the range of 50 degrees to 300 degrees, more preferably maintained at 100 degrees to 300 degrees.

The hard mask layer 130 may be formed in a single layer or multiple layers, and includes a component change section. At this time, it is preferable that the thickness of the hard mask film 130 is 50-150 GPa, and a sheet resistance is 1 kPa / square or less. In addition, when the hard mask layer 130 is formed as a multilayer, one or more of the same elements of adjacent thin films are continuously formed with a composition ratio change of 1 at% to 50 at% at a thickness of 5 nm or more at the interface of the adjacent thin films. It is desirable to be. In addition, the hard mask layer 130 includes at least one section in which the nitrogen content having a thickness of 5 nm or more is continuously changed, and the density change in the depth direction of the thin film is 0.2 to 2.0 g / cm ³ . Do. In addition, it is preferable that the hard mask layer 130 has a faster change in the etch rate in the depth direction than the surface portion in at least one or more sections. In addition, when the fluorine-based or chlorine-based dry etching, the selectivity with the metal film 120 located below the hard mask film 130 is preferably 5 or more.

Meanwhile, sputter targets used to form the hard mask layer 130 include molybdenum silicide (MoSi), molybdenum tantalum silicide (MoTaSi), chromium (Cr), tantalum (Ta), tungsten (W), and silicon. (Si), molybdenum (Mo), and titanium (Ti). In addition, the hard mask layer 130 is formed through a DC reactive magnetron sputtering method, wherein at least one selected from the group consisting of argon (Ar), helium (He), neon (Ne), and xenon (Xe) or a mixture thereof It is used as an inert gas and uses oxygen (O ₂ ), nitrogen (N ₂ ), carbon monoxide (CO), carbon dioxide (CO ₂ ), nitrogen dioxide (NO ₂ ), nitrogen monoxide (NO), nitrous oxide (N ₂ O), ammonia ( One or a mixture thereof selected from the group consisting of NH ₃ ) and methane (CH ₄ ) may be used as the reactive gas.

The resist film 140 is made of a resist material containing a strong acid and has a thickness of 1,000 to 2,000 kPa. In addition, it is preferable that an organic thin film having a thickness including a strong acid having a higher concentration than that of the resist film 140 is 200 GPa or less below the resist film 140. At this time, the organic thin film disposed below the resist film 140 is developed by a developer regardless of whether the exposure process is applied. The resist material coated on the surface of the hard mask layer 130 is a chemically amplified resist.

2 is a flowchart illustrating a manufacturing process of a blank mask for a hard mask according to the present invention.

Referring to FIG. 2, a sputter target having a composition ratio of Mo: Si of 1: 9 (that is, Mo: Si = 10 at%: 90 at%) manufactured on a 6025 transparent substrate 110 by HIP method is used. The metal film 120 is formed by applying the long through sputtering equipment as shown in FIG. 3 (S200). Process conditions during deposition of the metal film 120 are as described in the following table.

Process conditions Setting value Power 0.7 kW Argon Gas Inflow 5 sccm Process pressure 0.05 Pa

After performing the deposition process for the metal film 120 for 50 seconds under the process conditions as shown in Table 2 and deposited for 10 seconds by gradually changing the inflow of nitrogen such as 1.0 → 1.5 → 2.0 (sccm) A component change section is formed in the metal film 120. In addition, the flow rate of nitrogen is continuously changed as 5.0 → 9.0 → 13.0 → 9.0 → 5.0 (sccm) without turning off the plasma, and the power is sequentially increased from 0.7 → 1.0 → 1.2 → 1.5 (kW). Formed. The optical density and reflectance of the metal film 120 prepared as described above were analyzed using an analyzer (n & k Analyzer 1512RT equipment). 49 points were measured in the range, and the thickness was measured using a GXR instrument. As a result, the average optical density was 3.0 for the exposure light of 193 nm wavelength, the optical density uniformity was 0.02, the average reflectance was 18.3%, the reflectance uniformity was 0.52%, and the thickness was 483 Å, and the blank mask for the hard mask was shown. The metal film showed excellent characteristics.

In addition, the same metallurgical film 120 was immersed in 85% sulfuric acid and 23% SC-1 (hydrogen peroxide: ammonia water: ultrapure water = 1: 1: 5) for 2 hours, and then the same analytical equipment was used for reflectance change. It evaluated using. As a result, the reflectance change of 0.12% in sulfuric acid and 0.42% in SC-1 was shown with respect to exposure light having a wavelength of 193 nm, showing excellent performance as a metal film. In addition, the surface roughness of the 1 占 퐉 x 1 占 퐉 region was measured using an Atomic Force Spectrometer (AFM) device for the manufactured metal film 120, and exhibited excellent surface roughness characteristics by showing a value of 0.53 nmRa.

Next, the sputter target is replaced with a chromium target, and a hard mask film 130 is formed on the metal film 120 by the process conditions described in the following table (S210).

Process conditions Setting value Power 0.4 kW Process pressure 0.5 Pa Argon Gas Inflow 3 sccm Methane gas inflow 0.1 sccm Nitrogen Dioxide Gas Inflow 5 sccm

After performing the deposition process for the hard mask film 130 for 10 seconds under the process conditions as shown in Table 3, the inflow rate of nitrogen dioxide gas was sequentially adjusted as 5.0 → 3.0 → 1.0 (sccm) without turning off the plasma. Change, and the power was sequentially increased from 0.4 to 1.0 to 1.5 (kW) to form a component change section. As a result of measuring the sheet resistance of the hard mask layer 130 using the four-point probe device on the surface of the manufactured hard mask layer 130, it can be confirmed that the sheet has excellent sheet resistance characteristics by displaying 324 Ω / □. In addition, as a result of measuring the thickness of the hard mask film 130 by GXR equipment was confirmed to be 106 ,, it was measured using Auger Electron Spectrometer (AES) equipment in order to analyze the composition ratio of the blank mask manufactured for the hard mask. 4 is a graph illustrating a composition ratio analysis result of a hard mask film according to an exemplary embodiment of the present invention. Referring to FIG. 4, as a result of analyzing the composition ratio of the hard mask film according to the preferred embodiment of the present invention, it can be seen that the hard mask film includes a section in which the composition ratio of each atom is continuously changed.

Next, after forming an organic thin film containing a strong acid on the surface of the hard mask film 130 to a thickness of 100 kPa by spin coating, the FEP-171 positive chemically amplified resist material to a thickness of 1500 kPa Coating to prepare a blank mask for the hard mask (S220). The blank mask for hard mask manufactured in this way is manufactured into a photomask by the photomask process. At this time, the blank mask is written with an electron beam (E-beam) of 50 keV, and developed using a 2.38% THMA developer, and then the hard mask layer 130 is etched with chlorine gas. After removing the resist layer 140 again, the metal layer 120 is etched using the hard mask layer 130 as an etching mask. Next, the hard mask layer 130 is removed using a chromium etchant to complete the photomask. Then, the CD of the final patterned thin film was measured using CD-SEM, and as a result, it was confirmed that the CD of 50 nm was developed.

Hereinafter, evaluation results of the blank mask for the hard mask according to the present invention and the blank mask for the hard mask manufactured by a conventional staged film formation technique will be described. For evaluation, a blank mask was fabricated by the conventional stepwise deposition technique by performing the following process. First, a reactive DC magnetron sputtering method was applied using a sputter target having a Mo: Si composition ratio of 1: 9 (that is, Mo: Si = 10 at%: 90 at%) on a 6025 transparent substrate. A metal film was formed. The power used for deposition was 0.7 kW, the inflow of argon (Ar) gas was 5 sccm, the process pressure was 0.05 Pa, and the process time was 55 seconds. Thereafter, the plasma was turned off and an antireflection film was formed at a power of 1.5 kW with argon gas at 5 sccm and nitrogen gas at 10 sccm. The optical density and reflectance of the thin film formed stepwise by such process conditions were 8 mm sq. 49 points in the range were measured. And the thickness was measured at one point of the center using the GXR instrument. As a result of the measurement, the average optical density of the metal film deposited on the blank mask for hard mask manufactured by the conventional stepwise deposition technique was 3.0 for exposure light having a wavelength of 193 nm, the uniformity of optical density was 0.03, the average reflectance was 19.8%, The reflectivity uniformity was 1.12%, and the thickness was 512 GPa, so there was no big problem to use as a metal film of the blank mask for the hard mask.

Next, with respect to the metal film of the blank mask for a hard mask manufactured by the conventional stepwise film forming technique, it was immersed in 85 degrees sulfuric acid and 23 degrees SC-1 (hydrogen peroxide: ammonia water: ultra pure water = 1: 1: 5) for 2 hours. After the measurement, the change in reflectance was measured. As a result, it showed a change in reflectance of 0.52% with respect to sulfuric acid and 0.83% with respect to SC-1, which showed excellent performance as a metal film, but compared with the metal film containing the continuous film of the blank mask for a hard mask according to the present invention. It was confirmed that the chemical properties were bad. In addition, the surface roughness of the 1 μm × 1 μm region of the blank mask for the hard mask manufactured by the conventional stepwise deposition technique was measured using an AFM apparatus, and the value was 0.83 nmRa. Therefore, it can be seen that the surface roughness is reduced compared to the hard mask film 130 manufactured by the manufacturing method according to the present invention.

Next, the stuffer target was replaced with chromium, the flow rate of argon gas was set at 3 sccm, the flow rate of methane (CH4) gas was set at 0.1 sccm, and the flow rate of nitrogen dioxide gas was set at 5 sccm, and the power of 0.4 kW and 0.5 Pa The hard mask film was deposited on the metal film of the blank mask for the hard mask manufactured by the conventional stepwise film formation technique under a pressure of 12 seconds. The sheet resistance of the thin film measured using a four-point probe device on the surface of the conventional hard mask blank mask for a hard mask manufactured as described above was good at 402 Ω / □, and the thickness of the hard mask film measured by GXR was 116 Å. Indicated.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation in the embodiment in which said invention is directed. It will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the appended claims.

Claims (32)

In a blank mask comprising a transparent substrate, a metal film, a hard mask film and a resist film,
At least one of the metal film and the hard mask film includes a component change section that is a section in which the composition ratio of at least one element of the elements constituting the film is continuously changed in the depth direction of the film,
The blank mask, characterized in that the composition ratio uniformity is less than or equal to 10% in the width direction of the metal film. The method of claim 1,
The blank mask, characterized in that the composition ratio of the element in the component change period is changed in the range of 1 at% to 50 at%. The method of claim 1, wherein
And the metal film or the hard mask film has a multilayer structure in which a plurality of thin films are stacked, and at least one component change section is formed in the multilayer film. The method of claim 3, wherein
And when the component change section is formed inside the thin film of the multilayer structure, the thickness of the component change section is greater than or equal to 5 nm. The method of claim 1,
The blank mask, characterized in that the thickness of the component change period contained in the metal film is greater than or equal to 5 nm. The method of claim 1.
The thickness of the component change period contained in the metal film is greater than or equal to 1nm, and the blank mask, characterized in that the element whose composition ratio continuously changes in the depth direction of the metal film is nitrogen. The method of claim 1.
The blank mask, characterized in that the thickness of the component change period contained in the metal film is greater than or equal to 5 nm, the element is a composition ratio continuously changing in the depth direction of the metal film. delete The method of claim 1,
The blank mask, characterized in that the density change in the depth direction of the metal film is 0.2 g / cm ³ to 2.0 g / cm ³ . The method of claim 1,
The blank layer, characterized in that the metal film has a residual stress different in the depth direction of the film, and the difference in the residual stress is a difference occurs 10 MPa or more. The method of claim 1,
And a component change section on a surface of the metal film, wherein the surface roughness of the top surface of the component change section is less than or equal to 1.0 nmRa. The method of claim 1,
And said metal film comprises a component change period in which an element ratio of nitrogen is higher than an element ratio of oxygen in a range less than or equal to 5 nm in the depth direction from the surface. The method of claim 1,
The metal film includes a component change section, and the nitrogen content on the surface of the metal film is higher than the nitrogen content at a point spaced a predetermined distance from the surface in the depth direction. The method of claim 1,
And the hard mask layer comprises a component change section having a thickness greater than or equal to 20 microseconds. The method of claim 1,
The hard mask layer includes a component change section, wherein the change in the etch ratio of the point spaced apart a predetermined distance from the surface of the hard mask film is greater than the change in the etch ratio of the surface of the hard mask film. The method of claim 1,
The thickness of the component change period included in the hard mask film is greater than or equal to 1nm, the blank mask, characterized in that the element whose composition ratio is continuously changed in the depth direction of the metal film. The method of claim 1,
The blank mask, characterized in that the density change in the depth direction of the hard mask film is 0.2 g / cm ³ to 2.0 g / cm ³ . The method of claim 1,
And the resist film is formed of a resist material including a strong acid, and an organic thin film including a strong acid having a higher concentration than the resist film is formed under the resist film. The method of claim 1,
And the organic thin film formed under the resist film is developed by a developer. The method of claim 1,
And the transparent substrate is manufactured through a plurality of lapping processes and a plurality of polishing processes. The method of claim 20,
The plurality of lapping processes include a blank mask comprising abrasive particles comprising at least one of silicon carbide (SiC), diamond (C), zirconia (ZrO ₂ ), and alumina (Al ₂ O ₃ ). delete The method of claim 20,
The plurality of polishing processes are performed using a slurry comprising cerium oxide (CeO ₂ ), colloidal silica (SiO ₂ ) and hydrogen peroxide (H ₂ O ₂ ). delete delete delete A photo mask manufactured by patterning and etching the blank mask according to any one of claims 1 to 7, and 9 to 21 or 23. In the method of manufacturing a blank mask by sequentially forming a metal film, a hard mask film and a resist film on a transparent substrate,
(a) depositing a metal film on the transparent substrate such that the composition ratio uniformity is less than or equal to 10% in the width direction while maintaining the same process conditions for the first deposition time; And
(b) The composition ratio of at least one of the elements constituting the metal film is changed by changing stepwise or continuously among the plurality of process conditions constituting the process conditions applied during the second deposition time while the plasma is turned on. And forming a component change section which is a section continuously changing in the depth direction of the film.
Step (a) and step (b) is a blank mask manufacturing method, characterized in that performed in alternating order or alternately. The method of claim 28,
The process conditions include a reactive gas,
The reactive gas is a blank mask manufacturing method, characterized in that the nitrogen. The method of claim 28,
The process conditions include a reactive gas,
And the flow rate of the reactive gas is continuously increased and decreased, and the power of the plasma is continuously increased. In the method of manufacturing a blank mask by sequentially forming a metal film, a hard mask film and a resist film on a transparent substrate,
(a) depositing a metal film on the transparent substrate so that a composition ratio uniformity is less than or equal to 10% in a width direction during a first deposition time; And
(b) a composition ratio of at least one of the elements constituting the hard mask film by changing at least one of the plurality of process conditions constituting the process conditions applied during the second deposition time while the plasma is turned on in a stepwise manner or continuously; Forming a component change section which is a section continuously changing in the depth direction of the film. 32. The method of claim 31,
Forming an organic thin film containing a strong acid on the hard mask film; And
A method of manufacturing a blank mask, further comprising: forming a resist film by coating a resist material on the organic thin film.

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