KR20140035252A - Method for manufacturing mask blank and method for manufacturing transfer mask - Google Patents

Abstract

In the resist coating step for forming a resist film, a method for producing a mask blank and a transfer mask capable of suppressing generation of minute defects, in particular, defects caused by fine bubbles, in the resist film is obtained.
A method of manufacturing a mask blank comprising a resist coating step including a dropping step for dropping a resist solution, the method comprising: a rotation speed of the substrate at R (t), a drop start time of the resist solution at t _A , and when the end time of the dropwise addition to t _B, t _a ≤t≤t in the time range _B, (1) the relationship between _{R (t a) <R (} t B), (2) from t _a R (t _B ), R (t ₁ ) ≤R (t ₂ ) (t ₁ <t ₂ ), (3) 0≤R (t _A ) <700 rpm, and (4 The rotational speed R (t) of the substrate is changed so that the time from t _A to R (t _B ) is satisfied at least 0.1 second.

Description

The manufacturing method of the mask blank and the manufacturing method of the transfer mask {METHOD FOR MANUFACTURING MASK BLANK AND METHOD FOR MANUFACTURING TRANSFER MASK}

The present invention relates to a method for producing a mask blank and a transfer mask. In particular, the present invention relates to a method of manufacturing a mask blank and a method of manufacturing a transfer mask for manufacturing a semiconductor device using the same, which includes forming a resist film made of a resist material on a substrate.

In manufacturing the transfer mask by the photolithography method, a mask blank having a thin film (such as a light shielding film) for forming a transfer pattern (mask pattern) on a substrate such as a glass substrate is used. The manufacture of the transfer mask using the mask blank includes an exposure step of performing a desired pattern drawing on a resist film formed on the mask blank, a developing step of developing the resist film by forming a resist pattern in accordance with a desired pattern drawing, It is performed with the etching process of etching the said thin film according to a resist pattern, and the process of peeling and removing the remaining resist pattern. In the above development step, after the desired pattern drawing is performed on the resist film formed on the mask blank, a developer is supplied, and a portion of the soluble resist film is dissolved in the developer to form a resist pattern. In the above etching step, the resist pattern is used as a mask, and the exposed portion of the thin film on which the resist pattern is not formed is dissolved by dry etching or wet etching, whereby a desired mask pattern is formed on the light-transmissive substrate. do. In this way, the transfer mask is completed.

Conventionally, when forming a resist film by forming a resist film on a rectangular substrate or on a substrate with a thin film having a thin film deposited on the substrate, the resist is rotated using a rotary coating device that rotates the substrate to apply a resist liquid. Coating methods are generally used. As an example of this rotation coating method, Patent Document 1 describes a resist rotation coating method for forming a uniform resist film without forming a thick film at four corners of a substrate. Specifically, Patent Literature 1 discloses a homogenization step of substantially uniformizing the film thickness of a resist by rotating the substrate at a predetermined rotation speed and time, and at a rotation speed lower than the set rotation speed of the homogenization step following the homogenization step. A resist coating method is described, which comprises a drying step of rotating a substrate to substantially maintain the resist film thickness obtained by the homogenizing step and drying the uniformed resist.

In addition, Patent Literature 2 adds a resist liquid containing a resist material and a solvent onto a square substrate, rotates the substrate to spread the dropped resist liquid onto the substrate, A method for producing a mask blank, which comprises a step of drying a resist liquid on the substrate to form a resist coating film made of the resist material on the substrate, while the substrate is rotating in the step of forming the resist coating film. A mask blank is generated along the upper surface of the substrate from the central side of the substrate to generate an air flow, thereby suppressing liquid condensation of the resist liquid formed in the periphery of the substrate due to the rotation of the substrate. Processes for preparing are described.

Patent document 3 includes a spraying step of injecting a resist liquid onto a mask substrate, a diffusion step of rotating the mask substrate while varying the rotation speed, and diffusing the resist material over the entire mask substrate, and rotating the mask substrate to resist A method of manufacturing a blank mask is described, comprising a film forming step of forming a film and a drying step of rotating the mask substrate at a lower rotational speed than the film forming step to dry the resist film formed on the mask substrate. have. Patent Document 3 also describes that in the spraying step, when spraying a resist substance on the mask substrate, the rotation speed of the mask substrate is set to 150 rpm or less, and the spraying time is set to a range of 1 to 10 seconds. In addition, Patent Document 3 describes that the rotating state is maintained from the time point at which injection of the resist material is finished to the time point at which the next diffusion step is started.

Japanese Patent Publication Hei 4-29215 Japanese Patent Laid-Open No. 2005-12851 Republic of Korea Patent Registration No. 10-0818674

On the surface of the mask blank substrate, a thin film made of a metal compound, a silicon compound, or the like is formed, and a resist layer is formed on the surface of the thin film. In general, since the surface energy of a thin film made of a metal compound, a silicon compound, or the like is low, the surface of the thin film is likely to repel the applied resist liquid. If the wettability of the resist liquid is poor, the resist liquid may start to dry before it adheres to the surface of the thin film, whereby a bubble-shaped space may be formed between the surface to be coated and the resist layer. Such bubbles are, for example, fine defects of 100 nm or less.

In addition, a request for miniaturization of a mask pattern, for example, a request to make it suitable for a half pitch 45 nm node in a semiconductor device, has made it impossible to allow the attachment of minute foreign matter. For example, when dropping the resist liquid at a stop or at a low rotational speed, for example, at a rotational speed of 200 rpm or less, very fine foreign matters are not blown off by centrifugal force and are fixed. The phenomenon which remains on the surface may arise. In addition, when dropping a resist liquid at a stop or low rotational speed state, when the environment at the time of dropping is made into a reduced pressure, since the volatilization of the solvent of the resist liquid is promoted at the time of dropping of the resist liquid, foreign matters are easily fixed.

In order to suppress such a foreign material, the resist liquid to which surfactant was added is used. However, among the fine defects which occur at the time of image development, it is thought that surfactant added to the resist liquid is a generation factor. For this reason, in order to avoid the occurrence of defects due to the surfactant, a resist liquid in which the surfactant component is not added or in which the surfactant component is suppressed in a small amount is used. If the resist solution to which the surfactant has not been added is to be applied to the surface to be coated with low surface energy, naturally wettability deteriorates, and defects due to fine bubbles are generated.

Accordingly, the present invention provides a method for producing a mask blank and a transfer mask capable of suppressing the occurrence of minute defects in the resist film, in particular, the occurrence of defects due to minute bubbles, in a resist coating step for forming a resist film. The purpose.

This invention is a manufacturing method of the mask blank of the following structures 1-14 and the manufacturing method of the transfer mask of composition 15.

(Configuration 1)

The present invention provides a method for producing a mask blank comprising a resist coating step for forming a resist film made of a resist material on a substrate, wherein the resist coating step includes a resist material and a solvent on a square-shaped substrate. And a dropping step for dropping, wherein the dropping step is a rotational speed of the substrate when time t is R (t), a dropping start time of the resist solution is t _A , and a dropping end time of the resist solution is t when a _B, in the time range of _{t a ≤t≤t B, (1)} R (t a) when it reaches the <R related, (2) from t _a R (t _B) of (t _B) In the meantime, the relationship between R (t ₁ ) ≦ R (t ₂ ) and (3) 0 ≦ R (t _A ) <700 rpm for any time t ₁ and t ₂ with t ₁ <t ₂ and, (4) the time taken to reach from t _a R (t _B) and the rotational speed R (t) of the substrate is changed so as to satisfy the relationship 0.1 seconds or more , A method for manufacturing a mask blank, comprising.

(Composition 2)

In the manufacturing method of the mask blank of this invention, it is preferable that it is a relationship of R (t ₁ ) <R (t ₂ ) with respect to arbitrary time t ₁ and t ₂ in which the relationship of (2) is t ₁ <t ₂ . .

(Composition 3)

In the manufacturing method of the mask blank of this invention, it is especially preferable that the said rotational acceleration dR (t) / dt is constant.

(Composition 4)

In the production method of the mask blank of the present invention, the time to change in the time range until reaching a rotational speed R (t) is from t _A R (t _B) of the substrate, acceleration of the rotational speed R (t) It is preferable that the rotational acceleration dR (t) / dt is 10 rpm / s ≦ dR (t) / dt ≦ 1000 rpm / s.

(Composition 5)

In the production method of the mask blank of the present invention, and the rotation acceleration phases for the time range of the dropping step, t _A ≤t≤t _Y, accelerating the rotational speed R (t) of the substrate, t _Y <t≤t _In the time range of _Z , the rotational speed R (t) of the substrate includes a constant rotational speed maintenance step, and the relationship between the time t _Y at which the rotational speed maintenance step is started and the dropping end time t _B of the resist liquid t _Y ≤ t _B , the rotational speed R (t) (t _Y <t≤t _Z ) of the rotational speed maintaining step is R (t) ≥ 300 rpm, and the rotational acceleration dR (t in the rotational acceleration step ) / dt (t _A ≤ t ≤ t _Y ) satisfies 10 rpm / s ≤ dR (t) / dt ≤ 1000 rpm / s, and the rotational speed of the substrate is accelerated by the constant rotational acceleration. .

(Composition 6)

In the production method of the mask blank of the present invention, that the rotational speed _{R (t) (t Y <} t≤t Z) of the substrate of the rotary speed of the holding step 500 rpm≤R (t) ≤1000 rpm is preferred.

(Composition 7)

In the manufacturing method of the mask blank of this invention, it is preferable that the said resist coating process further includes the rest process which lowers the rotational speed of a said board | substrate or stops rotation after the said dripping process.

(Composition 8)

In the production method of the mask blank of the present invention, the resist coating step, preferably further includes the step of equalizing after the dropping step, rotating the substrate at a rotational speed of the substrate faster than R (t _B).

(Composition 9)

In the manufacturing method of the mask blank of this invention, it is preferable to include the prerotation process which raises a rotational speed step by step toward the high rotational speed of a homogenization process between the said pause process and the said homogenization process.

(Configuration 10)

In the manufacturing method of the mask blank of this invention, it is preferable to include operating the exhaust means for exhausting in order to produce | generate airflow toward the said board | substrate at the said homogenization process.

(Configuration 11)

In the method for producing a mask blank of the present invention, the surface on which the resist film of the substrate is formed is a surface of a thin film formed by a reactive sputtering method, and the thin film is at least Cr, Ta, Si, Mo, Ti, V, Nb and W. It is also preferably applicable to the surface containing at least one element selected from the group consisting of.

(Configuration 12)

In the method for producing a mask blank of the present invention, the surface for forming the resist film of the substrate is a surface of a thin film formed by a reactive sputtering method, the thin film contains at least Cr, and the proportion of Cr contained in the thin film is at least 50. It can apply especially to the surface of atomic% or more.

(Composition 13)

In the method for producing a mask blank of the present invention, the surface on which the resist film of the substrate is formed is a surface of a thin film formed by a reactive sputtering method, and the surface on which the resist film of the substrate is formed is a surface of a thin film formed by a reactive sputtering method. The thin film is particularly preferably applied to a surface containing at least Si.

(Composition 14)

In the manufacturing method of the mask blank of this invention, it is applicable also when the said resist liquid does not contain surfactant substantially.

(Composition 15)

In the present invention, a resist pattern is formed by patterning the resist film of the mask blank manufactured by the method for producing a mask blank according to any one of Configurations 1 to 14, and a mask pattern is formed using the resist pattern as a mask for transfer. It is a manufacturing method of the transfer mask characterized by manufacturing a mask.

According to the present invention, in the above-mentioned resist coating step for forming a resist film, there is obtained a method for producing a mask blank and a transfer mask capable of suppressing occurrence of minute defects in the resist film, in particular, occurrence of defects due to minute bubbles. Can be.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the relationship between the time and the rotation speed of a board | substrate in a resist coating process. The dotted line shows the case where the resist application process has a rotation initial stage SO.
2 is a flowchart illustrating an example of a procedure of a resist coating step.
It is a side cross-sectional schematic diagram which shows an example of a rotary coating device.
It is a schematic diagram which shows an example of (A) board | substrate with a thin film, (B) mask blank, and (C) transfer mask.
It is a cross-sectional schematic diagram which shows an example of the mask blank provided with the light shielding film and the etching mask film on a board | substrate.

The method for producing a mask blank of the present invention is characterized in that the dropping of the resist liquid is performed while accelerating the rotational speed of the substrate in the dropping step for dropping the resist liquid on the substrate to form a resist film made of a resist material. have. The present inventors have found that, by the coating method of dropping the resist liquid while accelerating the rotational speed of the substrate, the resist liquid can be smoothly spread on the surface to be coated at the initial stage of dropping of the resist liquid. The present inventors also found that even when the surface to be coated has a relatively low surface energy, the entire surface to be coated can be wetted with a resist liquid, so that defects due to fine bubbles are hardly generated. Invented.

In the manufacturing method of the mask blank 10 of this invention, first, the board | substrate 15 with a thin film in which the predetermined | prescribed thin film 14 was formed in the surface of the board | substrate 11 is prepared (FIG. 4A). Subsequently, the mask blank 10 of the present invention is manufactured by forming a resist film 16 by dropping and applying the resist liquid 26 on the surface of the thin film 14 of the substrate 15 with thin film by a predetermined method. It can be (FIG. 4B). By performing predetermined patterning on the thin film 14 of the mask blank 10 of this invention, the transfer mask 18 which has the mask pattern 13 for transferring to a to-be-transferred body can be manufactured (FIG. 4). (C)).

As the board | substrate 11 used for the manufacturing method of the mask blank 10 of this invention, a glass substrate can be used. It will not specifically limit, if it is used as the mask blank 10 as a glass substrate. For example, synthetic quartz glass, soda-lime glass, aluminosilicate glass, borosilicate glass, an alkali free glass, etc. are mentioned. Moreover, in the case of the glass substrate for reflective mask blanks (for EUV mask blanks), in order to suppress the deformation | transformation of the transfer pattern by the heat at the time of exposure, it is in the range of about 0 +/- 1.0x10 <^-7> / ^degreeC Preferably a glass material having a low thermal expansion coefficient in the range of about 0 ± 0.3 × 10 ⁻⁷ / ° C. is used. In addition, since many thin films are formed on a glass substrate, EUV mask blank has a high rigidity glass material which can suppress deformation due to film stress. As the board | substrate 11, the glass material which has a high Young's modulus especially 65 GPa or more is preferable. For example, a SiO ₂ -TiO ₂ type glass, amorphous glass or synthetic quartz glass, a crystallized glass β- quartz solid solution precipitated the like are used.

It is preferable that the shape of the board | substrate 11 used for the manufacturing method of the mask blank 10 of this invention is square shape. In general, it is not easy to apply the resist liquid 26 evenly to each part of the substrate 11. On the other hand, when the mask blank 10 manufacturing method of the present invention is used, the resist film 26 can be uniformly applied to each part of the substrate 11 to obtain a resist film 16 in which defects are suppressed. have.

As for the substrate 15 with a thin film used for the manufacturing method of the mask blank 10 of this invention, the thin film 14 is formed into a main surface of the square-shaped board | substrate 11 using sputtering method, vapor deposition method, or CVD method. It can manufacture by doing.

The thin film 14 causes an optical change with respect to the exposure light (for example, an ArF excimer laser, etc.), specifically, a light shielding film for shielding the exposure light, or a phase shift film for changing the phase of the exposure light (this phase shift). Examples of the film include a halftone film having a light shielding function and a phase shift function), and a thin film having a laminated structure composed of a multilayer reflective film used for a reflective mask blank, an absorber and an etching mask.

Examples of the light shielding film include films of Cr-based compounds, Ta-based compounds, W-based compounds, transition metal silicides such as MoSi, and transition metal silicide compounds such as MoSiN.

As a phase shift film, the film of transition metal silicide compounds, such as MoSiO, MoSiON, MoSiN, is mentioned, for example.

The thin film 14 of a phase shift mask blank and a binary mask blank is not limited to a single layer, The laminated film which laminated | stacked several layers, such as an etching stopper layer and an etching mask layer, in addition to the said light shielding film and a phase shift film can be used. . As a laminated film of the thin film 14, the laminated film of the light shielding film, the laminated film which laminated | stacked the phase shift film, and the light shielding film, etc. are mentioned, for example.

The multilayer reflective film is a multilayer reflective film applicable to EUV light, and includes Si / Ru periodic multilayer film, Be / Mo periodic multilayer film, Si compound / Mo compound periodic multilayer film, Si / Nb periodic multilayer film, Si / Mo / Ru periodic multilayer film, Si / Mo. / Ru / Mo periodic multilayer films, Si / Ru / Mo / Ru periodic multilayer films, and the like. On the surface of the multilayer reflective film, an absorber layer made of Ta-based material or the like is formed, and an etching mask film made of Cr-based compound is formed thereon.

As the mask blank 10 which can be manufactured by the manufacturing method of the mask blank 10 of this invention, a binary mask blank, a phase shift type mask blank, and a reflective mask blank are mentioned. In the case of a binary mask blank and a phase shift type mask blank, as a board | substrate 11, the translucent board which consists of synthetic quartz glass is used. As a binary mask blank, the mask blank in which the light shielding film was formed as the thin film 14 is mentioned, and the mask blank in which the phase shift film (including a halftone film) was formed as the thin film 14 is mentioned as a phase shift mask blank.

In the case of the reflective mask blank, a low thermal expansion glass (such as SiO ₂ -TiO ₂ glass) having a small thermal expansion coefficient is used as the substrate 11, and a light reflection multilayer film and a mask pattern 13 are formed on the substrate 11. Is formed by sequentially forming a light absorber film. In the case of the reflective mask blank, these light reflection multilayer films, light absorber films, and etching mask films are thin films 14.

The manufacturing method of the mask blank 10 of this invention includes the resist coating process for forming the resist film 16 which consists of a resist material on the board | substrate 11 (substrate 15 with a thin film). In the method of manufacturing the mask blank 10 of the present invention, it is possible to form the resist film 16 directly on the substrate 11. However, in general, since the resist film 16 is formed on the surface of the substrate 15 with a thin film, in the following, the resist liquid 26 is applied to the surface of the thin film 14 of the substrate 15 with a thin film. It demonstrates. However, in this specification, for example, the "substrate with thin film 15" may be simply referred to as "substrate." In particular, since both the "rotational speed of a board | substrate" and the "rotational speed of the thin film substrate 15" represent the rotational speed of the rotation coating device 20, both have the same meaning.

In FIG. 1, the relationship between the time in the resist coating process of the manufacturing method of this invention, and the rotation speed of the board | substrate 15 with a thin film is shown. 2, the flowchart which shows an example of the procedure of the resist coating process of the manufacturing method of this invention is shown. 3 is a side cross-sectional view of an example of the rotary coating device 20 for forming the resist film 16 by applying the resist liquid 26 to the surface of the thin film 14 of the substrate 15 with thin film. do.

The resist coating process in the manufacturing method of the mask blank 10 of this invention is demonstrated, referring FIG. 1, FIG. 2, and FIG. As shown in FIG. 2, the resist coating process in the manufacturing method of the mask blank 10 of this invention includes the dripping process containing a rotation acceleration step S1. The dripping process may further include a rotational speed maintaining step (S2). In addition, the resist coating process in the manufacturing method of the mask blank 10 of this invention is a rest process (S3), a pre-rotation process (acceleration) (S4), a pre-rotation process (hold) (S5), and a uniformity process ( S6) and a drying process (S7) can be included as needed. In addition, the resist coating process may further include an initial rotation step S0 before the rotation acceleration step S1.

As shown in FIG. 3, the spin coating device 201 spins and holds a spinner chuck 21 rotatably holding a substrate 15 having a thin film formed thereon, for example, on a rectangular substrate 11. ), The nozzle 22 for dropping the resist liquid 26 onto the thin film substrate 15, and the dropped resist liquid 26 are rotated by the thin film substrate 15. The cup 23 for preventing scattering around the rotary coating device 20 after scattering to the outside, and the resist liquid 26 scattered to the outside of the substrate 15 with the thin film on the upper side of the cup 23 The inner ring 24 which leads to the outer side downward of the cup 23, and the exhaust means 30 which exhausts so that the air flow 34 toward the board | substrate 15 with a thin film may be produced are provided.

The above-described spinner chuck 21 is connected to a motor (not shown) for rotating the substrate 15 with a thin film, and the motor rotates the spinner chuck 21 based on the rotation conditions described later.

Further, below the cup 23, a liquid for recovering the liquid by recovering the exhaust means 30 provided with the exhaust amount control means for controlling the exhaust amount and the resist liquid 26 scattered out of the substrate 15 with the thin film during rotation. Discharge means (not shown) is provided.

In the resist coating process using the said rotary coating device 20, the board | substrate 15 with a thin film is first conveyed to the spinner chuck 21 of the rotary coating device 20 by a board | substrate conveying apparatus (not shown), The substrate 15 with the thin film is held on the spinner chuck 21.

The resist coating step then includes a dropping step for dropping a resist liquid 26 containing a resist material and a solvent on a rectangular thin film-attached substrate 15, as shown in FIGS. 1 and 2. . Specifically, the resist liquid 26 is dripped from the nozzle 22 of the rotary coating device 20 to the surface of the thin film 14 of the substrate 15 with a thin film.

The dropping step includes a rotational acceleration step S1 in which the rotational speed of the thin film-attached substrate 15 changes rapidly. The manufacturing method of the mask blank 10 of this invention rotates the board | substrate 15 with a thin film at predetermined | prescribed rotational speed through the spinner chuck 21 by a motor at the time of a dropping process, and accelerates the rotational speed. This is characterized by dropping the resist liquid 26.

In the manufacturing method of the mask blank 10 of this invention, the dropping start time of R (t) and the resist liquid 26 are set to the rotational speed of the board | substrate 11 (the board | substrate with thin film 15) at the time t. _When the dropping end time of _A and the resist liquid 26 is t _B , the substrate 11 (the substrate 15 with a thin film) is satisfied so as to satisfy the following four conditions in a time range of t _A ≤ t ≤ t _B. The rotational speed R (t) is changed.

(1) Relationship between R (t _A ) ≤R (t _B )

(2) R (t ₁ ) ≤R (t ₂ ) for any time t ₁ and t ₂ with t ₁ <t ₂

(3) the relationship between 0 ≦ R (t _A ) <700 rpm and

(4) The relationship from t _A to R (t _B ) is 0.1 seconds or more.

The relationship of the condition (1) means that the rotational speed R (t _B ) of the substrate at the dropping end time t _B is faster than the rotational speed R (t _A ) of the substrate at the dropping start time t _A. In the example shown in FIG. 1, the acceleration of the rotational speed of the substrate is started at a time t _X equal to the drop start time t _A of the resist liquid 26, and the time t before the drop end time t _B of the resist liquid 26. _{It shows that Y} reached the rotational speed R (t _B ). The rotation acceleration step S1 is a period from the acceleration start time t _X to the acceleration end time t _Y of the substrate 11. Also, a degree in the example shown in _A 1 t = _X t, condition (1) if it is satisfied the relations to (4) need not necessarily be t _A = t _X. In addition, acceleration end time t _Y may be earlier than dripping end time t _B of the resist liquid 26.

The relationship of condition (2) means that between the dripping start time t _A and dripping end time t _B , the rotational speed R (t) of a board | substrate does not decelerate but monotonically increases and accelerates. When the rotational speed R (t) of the substrate is accelerating, the resist liquid 26 is dropped, so that the resist liquid 26 is gently brought into the surface of the substrate 15 with a thin film in the initial stage of dropping of the resist liquid 26. Can be smeared on. As a result, even if it is the surface of the board | substrate 15 with a thin film with a relatively low surface energy, since the whole surface can be wetted with the resist liquid 26, the defect resulting from the bubble of the resist liquid 26 hardly arises. In the example shown in Figure 1, between the start of acceleration from time t _X t _Y to the acceleration end time, the rotational speed of the substrate, and is accelerated to a predetermined rotational acceleration. However, as long as it satisfies all the relations of the conditions (1) to (4), it is not necessarily accelerated with a constant rotational acceleration, and may maintain the same rotational speed for a short time. Further, according to the relationship between the condition (1), was added dropwise a start time t _A and a dripping end time _between t _B, the rotational speed R (t) of the substrate does not slow down the rotational speed and the rotational speed of the substrate R (t _B ), That is, after the acceleration end time t _Y at which the rotation speed reaches the rotation speed R (t _B ), the rotation speed R (t _B ) is maintained at least until the dripping end time t _B of the resist liquid 26. It becomes necessary.

Further, is "to maintain the rotational speed R (t _B)", and changes will not adversely affect the degree rotation speed with respect to the application of the resist solution 26 according to the method of the present invention, for example, rotation of ± 30% Fluctuations in speed, preferably fluctuations in rotation speed of ± 20%, more preferably fluctuations in rotation speed of ± 10%, and still more preferably fluctuations in rotation speed of ± 5%.

The time range from the time t _Y to the time t _Z to maintain the rotational speed R (t _B ) is called the rotational speed maintenance step S2. In the example shown in Figure 1, inde t _B = t _Z, condition (1) if it is satisfied the relations to (4), it is not necessarily the t _B = t _Z. That is, the end time of a rotational speed holding phase (S2) prior to the t _Z, may shut down the dropping of the resist solution 26. Rotational speed maintenance step S2 is not necessarily essential. However, by having the rotational speed maintaining step S2, by continuously dropping the resist liquid 26 while maintaining the rotational speed of the substrate at a high speed, excessive drying in the dropping step can be suppressed, so that a film thickness variation occurs. It is difficult to do. In addition, the foreign matter can be efficiently removed from the surface to be coated by the high speed rotation. Therefore, it is preferable that the dripping process of the manufacturing method of the mask blank 10 of this invention includes rotation speed maintenance step S2.

Further, condition (2) according to the relationship, while until reaching a from dropping start time t _A ends the rotational speed R (t _B) of the substrate of time dropping, t ₁ <t _2, the arbitrary time t ₁ and the to related parties of the _{R (t 1) <R (} t 2) with respect to t ₂ is preferred. That is, from the drop start time t _A until the rotation speed R (t _B ) of the substrate at the end of the drop time is reached, the rotation speed of the substrate is not changed constantly but is always changed to accelerate and continues to accelerate. It is preferable. By continuously accelerating the rotational speed of the substrate, it is possible to more reliably suppress the occurrence of defects due to bubbles in the resist liquid 26.

The relationship of condition (3) means that the rotational speed of the substrate at the dropping start time t _A is less than 700 rpm, and the rotation of the substrate may be stopped (R (t _A ) = 0) at the start of dropping. By setting the rotational speed of the substrate at the dropping start time t _A to a predetermined low rotational speed, the dropped resist liquid 26 wets the entire surface of the substrate 15 with a thin film without bubbles, thereby causing the bubbles of the resist liquid 26 to disappear. It can prevent occurrence. The rotational speed of the substrate at the dropping start time t _A is less than 700 rpm, preferably 500 rpm or less, more preferably 100 rpm or less, still more preferably 50 rpm or less, particularly preferably at the instant of dropping start. By the rotation of the substrate being stopped, generation of defects caused by bubbles in the resist liquid 26 can be prevented.

The relationship of the condition (4) is that the time from the dropping start time t _A to the same rotational speed as the rotational speed R (t _B ) of the substrate at the dropping end time t _B , that is, the dropping start time t _It means that the time from _A to the end of acceleration of the rotational speed of a board | substrate is 0.1 second or more.

In relation to condition (4), specifically, when the rotational speed R (t) of the substrate changes in the time range from t _A to R (t _B ), the rotational speed R (t) of the substrate It is preferable that the rotational acceleration dR (t) / dt which is an acceleration of) is 10 rpm / s ≦ dR (t) / dt ≦ 1000 rpm / s. Moreover, it is preferable that acceleration dR (t) / dt of the rotational speed R (t) of a board | substrate is constant. By the constant acceleration of the rotational speed of the substrate at a predetermined rotational acceleration, it is possible to more reliably suppress the occurrence of defects caused by bubbles in the resist liquid 26.

With reference to FIG. 1 and FIG. 2, the preferable aspect is demonstrated about the resist coating process in the manufacturing method of the mask blank 10 of this invention.

As it is shown in Figs. 1 and 2, a dropping process, in the time range of t _A ≤t≤t _Y, and rotational acceleration step (S1) for accelerating the rotational speed R (t) of the substrate, _Y t <t In the time range of ≤ t _Z , it is preferable that the rotational speed R (t) of the substrate includes a constant rotational speed maintaining step S2. In this case, the relationship between the time t _{Y at} which the rotational speed maintaining step S2 is started and the dripping end time t _B of the resist liquid 26 is t _Y ≦ t _B. That is, the dropping of the resist liquid 26 can be performed from the start time t _Y to the end time t _{Z in} addition to the rotation acceleration step S1. In order to suppress excessive drying in the dropping step and make it difficult for foreign matters to settle on the surface of the substrate 15 with a thin film, the dropping of the resist liquid 26 is performed until the end time t _Z of the rotational speed maintaining step S2. desirable.

The rotational speed R (t) (t _Y < t? T _Z ) of the rotational speed maintenance step S2 can be adjusted according to the type of the resist liquid 26. In order to stabilize the shape after completion of the dropwise addition of the resist liquid 26 and to suppress excessive drying, it is generally preferable that R (t) ≥ 300 rpm, and that 500 rpm ≤ R (t) ≤ 1000 rpm. More preferred.

The rotational acceleration dR (t) / dt (t _A ≤t≤t _Y ) in the rotational acceleration step S1 satisfies 10 rpm / s≤dR (t) / dt≤1000 rpm / s, and at a constant rotational acceleration It is preferable that the rotational speed of the substrate is accelerated by this. Thereby, generation | occurrence | production of the defect resulting from the bubble of the resist liquid 26 can be prevented more reliably, and control of the rotation speed in rotation acceleration step S1 becomes easy.

In the method of manufacturing the mask blank 10 of the present invention, the resist coating process may include an initial rotation step S0. In FIG. 1, the time change of the rotational speed of a board | substrate when the resist coating process has a rotation initial stage S0 is shown by the dotted line. By rotating the board | substrate 15 with a thin film before the dropping of the resist liquid 26, the foreign material on the surface of the board | substrate 11 can be removed by the centrifugal force of rotation. The rotational speed of the substrate in the initial rotation step S0 is less than 700 rpm, preferably 500 rpm or less, more preferably 100 rpm or less, even more preferably 50 rpm or less, so that the surface of the substrate 15 with thin film The removal of foreign matters and the prevention of defects caused by bubbles in the resist liquid 26 can be performed together.

In the method for producing the mask blank 10 of the present invention, the resist coating step may further include a rest step S3 for lowering the rotational speed of the substrate or stopping the rotation after the dropping step. In addition, the manufacturing method of the mask blank 10 of this invention is the pre-rotation process which raises a rotational speed step by step toward the high speed rotational speed of the homogenization process S6 between the rest process S3 and the homogenization process S6 ( S4 and S5).

When the process proceeds to the homogenization step S6 in the state where the high speed rotation is continued in the rotational speed maintaining step S2, liquid condensation of the resist liquid 26 biased to the edge of the substrate 15 with thin film may occur. . By including the step S3 of slowing down or stopping the rotational speed of the substrate once before the resist coating step proceeds to the homogenization step S6, the centrifugal force applied to the resist liquid 26 at the edge portion can be reduced. Therefore, liquid condensation of the edge part of the board | substrate 15 with a thin film can be suppressed. In addition, since the resist coating step includes the pre-rotation steps (S4 and S5), it can be accelerated step by step toward the high-speed rotation (S4), and can be maintained in a state where the rotation speed is lower than the rotation speed of the homogenization step (S6) (S5). have. By having a free rotation process, the rotation speed of a board | substrate can be raised in steps toward the high speed rotation speed of a homogenization process. As a result, since the homogenizing step S6 can be performed in the state where the resist liquid 26 is even on the surface of the substrate 15 with thin film, the phenomenon of liquid condensation can be suppressed particularly effectively.

In the production method of the mask blank 10 according to the present invention, the resist film forming process, after the dropping step, a dripping end time t _B the rotation of the substrate the substrate at a rotational speed of the rotational speed of the faster the substrate than the R (t _B) of the time It may include a homogenization step (S6). When the resist coating step has a homogenization step (S6), the film thickness of the resist film on the substrate 15 with thin film can be made uniform. When the resist coating step includes the rest step S3 and the free rotation steps S4 and S5, the homogenization step S6 is performed after those steps S3 to S5. The rotational speed and rotation time of the substrate in the homogenization step S6 are set according to the kind of the resist liquid 26. In general, the rotation speed of the substrate in the homogenization step S6 is preferably 850 to 2000 rpm, and the rotation time is preferably 1 to 15 seconds.

The manufacturing method of the mask blank 10 of this invention makes it possible to operate the exhaust means 30 for exhausting in order to produce | generate the airflow 34 which goes to the board | substrate 15 with a thin film in the homogenization process S6. It is preferable to include the thing. Actively reducing the coating environment in the dropping step promotes volatilization of the solvent contained and causes the resist liquid 26 to dry before being brought into close contact with the surface to be coated, or to cause the resist liquid 26 to dry. Dry aggregation can be suppressed.

In the homogenizing step S6, the substrate 15 with the thin film is attached along the upper surface of the substrate 15 with thin film while the substrate 15 with the thin film is rotated by the exhaust means 30 equipped with the displacement control means for controlling the displacement. The airflow 34 can be generated so that the airflow 34 flows in the outer circumferential direction from the center side of 15. By the airflow 34, liquid condensation of the resist liquid 26 generated on the outer peripheral portion (the main surface end of the substrate 11) of the thin film substrate 15 can be effectively scattered out of the thin film substrate 15. Since liquid condensation of the resist liquid 26 generated at the four corners of the thin film substrate 15 and the outer peripheral portion of the thin film substrate 15 can be effectively suppressed from being returned to the center portion of the thin film substrate 15, the substrate with thin film ( The thick film region of the resist film 16 formed at the four corners and the peripheral portion of 15) can be reduced, or the swelling of the film thickness of the region can be reduced (restriction of the thick film). Specifically, it is preferable to control the displacement so that the speed of the air flow 34 that reaches the upper surface of the thin film substrate 15 is 0.5 m / sec or more and 5 m / sec or less.

In addition, by controlling the height (distance) to the inner ring 24 (opening part 32) provided on the upper surface of the substrate 15 with the thin film and the cup 23 upper side, and the opening diameter of the inner ring 24, the thin film is attached. By controlling the flow rate of the airflow 34 that contacts the outer peripheral portion of the substrate 15 with the thin film from the upper surface of the substrate 15, the resist liquid 26 generated on the outer peripheral portion (the main surface end of the substrate 11) of the thin film substrate 15 is controlled. Liquid condensation is effectively scattered out of the thin film substrate 15, and liquid condensation of the resist liquid 26 that occurs in the four corners of the thin film substrate 15 and the outer peripheral portion of the thin film substrate 15 is carried out. It is possible to maintain the flow rate necessary for being able to effectively suppress the return to the center part.

In addition, generation | occurrence | production of the airflow 34 by the exhaust means 30 can be performed not only in the homogenization process S6, but also in another process, for example, drying process S7.

In the manufacturing method of the mask blank 10 of this invention, a resist coating process can include a drying process (S7). In the drying step S7, after the homogenization step S6, the substrate 15 with the thin film is rotated at a rotational speed lower than the rotation speed in the homogenization step S6, so that the resist film 16 obtained in the homogenization step S6 is rotated. The resist film 16 can be dried while maintaining the uniformity of the film thickness.

In the manufacturing method of the mask blank 10 of this invention, in order to completely evaporate the solvent contained in the resist film 16 formed on the board | substrate 15 with a thin film after completion | finish of drying process S7 mentioned above, this resist film is carried out. You may have the heat-drying process of heating and drying (16). This heat-drying process is a heating process which heats the board | substrate 15 with a thin film in which the resist film 16 was formed with a heating plate normally, and the board | substrate with a thin film 15 in which the resist film 16 was formed to a cooling plate. It includes the cooling process to cool by. The heating temperature and time in these heating processes, and the cooling temperature and time in a cooling process are adjusted suitably according to the kind of resist liquid 26. As shown in FIG.

In the manufacturing method of the mask blank 10 of this invention, although the said resist liquid 26 is not specifically limited, High molecular type resist which consists of high molecular weight resin whose viscosity exceeds 10 mPa * s and average molecular weight is 100,000 or more, A novolak-type resist consisting of a novolak resin having a viscosity of less than 10 mPa · s and an average molecular weight of less than 100,000, a dissolution deliquescent agent, a chemically amplified resist comprising a polyhydroxystyrene-based resin, an acid generator, or the like. to be.

For example, in chemically amplified resists and novolac resists, since the viscosity is low (10 mPa · s or less), in the homogenization step (S6), the rotation speed of the substrate is 850 to 2000 rpm, so that the substrate 11 The rotation time is set to 1 to 10 seconds, respectively, and in the drying step S7, the rotation speed of the substrate is set to 100 to 450 rpm. In the polymer type resist, the viscosity is high (more than 10 mPa · s), so in the homogenization step S6, the rotation speed of the substrate is 850 to 2000 rpm, and the rotation time of the substrate 11 is 2 to 15 seconds, respectively. In the drying step S7, the rotational speed of the substrate is set to 50 to 450 rpm. The rotation time of the substrate 11 in the drying step S7 is until the resist film 16 is completely dried (until the further drying rotation is continued until the film thickness of the resist film 16 does not decrease). The time required is set.

It is preferable that the final discharge amount of the resist liquid 26 in a resist coating process is 1.5-8 ml. If it is less than 1.5 ml, the resist liquid does not spread widely enough on the substrate surface, and there is a fear that the film forming state will deteriorate. If it exceeds 8 ml, the amount of the resist liquid which is not used for coating and scatters to the outside by spin rotation increases, which is not preferable because the consumption amount of the resist liquid increases. In addition, there is a fear that scattered resist liquid may contaminate the inside of the coating apparatus.

Moreover, it is preferable that the discharge speed of the resist liquid 26 is 0.5-3 ml / sec. If the discharge rate is less than 0.5 ml / sec, a problem arises that the time for supplying the resist liquid on the substrate becomes long. When the discharge rate exceeds 3 ml / sec, the resist liquid is strongly in contact with the substrate, and the resist liquid may be thrown out without wetting the substrate, which is not preferable.

In the manufacturing method of the mask blank 10 of this invention, it is preferable that the resist liquid 26 does not contain surfactant substantially. The defect which thinks that surfactant added to the resist liquid 26 is one of the factors which generate | occur | produces a fine foreign material may arise at the time of image development. Since the resist liquid 26 does not substantially contain surfactant, generation | occurrence | production of a foreign material can be reduced.

In the method of manufacturing the mask blank 10 of the present invention, the surface on which the resist film 16 of the substrate 15 with thin film is formed is the surface of the thin film 14 formed by the reactive sputtering method, and the thin film 14 is at least. It is preferable to contain at least one element selected from the group consisting of Cr, Ta, Si, Mo, Ti, V, Nb and W. Since the surface energy of the surface of the thin film 14 containing these elements is low, when the resist liquid 26 is dropped on the surface of the substrate 15 with a thin film (surface of the thin film 14), the resist liquid 26 is dropped. Especially easy to bounce. By using the method of manufacturing the mask blank 10 of the present invention, the resist liquid 26 can be prevented from being thrown off the surface of the thin film 14, and therefore, a preferable resist film that suppresses the occurrence of defects due to fine bubbles (16) can be formed.

In the method for manufacturing the mask blank 10 of the present invention, the thin film 14 having the surface (coated surface) for forming the resist film 16 contains at least Cr, and the proportion of Cr contained in the thin film 14 is It is preferable that it is at least 50 atomic% or more. In the case where the surface to be coated contains Cr, for example, CrN, CrON, CrOC, CrOCN, or the like, the wettability of the surface to be coated with the resist liquid 26 is poor, so that defects due to fine bubbles are likely to occur. By using the manufacturing method of the mask blank 10 of this invention, even if the to-be-coated surface is a thin film containing Cr, the resist film 16 with which the defect was reduced can be formed.

In addition, as shown in FIG. 5, the thin film containing Cr may be provided as the etching mask film 3 of the upper surface of the light shielding film 2. As shown in FIG. This etching mask film contains at least any one component of nitrogen and oxygen in chromium, and content of chromium in this etching mask film is 50 atomic% or more. As shown in FIG. 5, the mask blank 10 includes a light shielding film 2 on a light transmissive substrate 11 and a mask blank including an etching mask film 3 on the light shielding film 2. (10).

In the example shown in FIG. 5, the said etching mask film 3 is nitrogen, for example, in chromium so that etching selectivity with the light shielding film 2 can be ensured with respect to dry etching at the time of patterning for forming a transfer pattern. It is preferable to use a material containing at least one component of oxygen. By providing such an etching mask film 3 on the light shielding film 2, the resist film 16 formed on the mask blank 10 can be thinned. Moreover, you may further contain components, such as carbon, in the etching mask film 3. Specifically, materials, such as CrN, CrON, CrOC, CrOCN, are mentioned, for example.

In recent years, the method of exposing a design pattern by applying the resist for electron beam drawing exposure to the resist film 16, and irradiating and drawing an electron beam (electron beam exposure drawing) is used. In the electron beam drawing exposure, at least one of the light shielding film 2 and the etching mask film 3 is required to have a certain level of conductivity from the viewpoint of drawing position accuracy and charge up. That is, it is desired that the sheet resistance value be 1.0 × 10 ⁶ Ω / □ or less in at least one of the light shielding film 2 and the etching mask film 3.

When the sheet resistance value of the light shielding film 2 is 1.0 * 10 <^{6> (} ohm) / (square) or less, even if the sheet resistance value is high, an electron beam drawing can be carried out without a charge up. It is more preferable to improve the etching rate of dry etching with respect to the mixed gas of chlorine and oxygen of the etching mask film 3 for thinning the resist film 16. For that purpose, it is preferable to make content of a metal component (chrome) into less than 50 atomic%, Preferably it is 45 atomic% or less, Furthermore, it is 40 atomic% or less.

On the other hand, when the sheet resistance of the light-shielding film ^{(2) 1.0 × 10 6 Ω} / □ is larger than, it is necessary to the sheet resistance of the etching mask film 3 is less than 1.0 × 10 ⁶ Ω / □. In this case, when the etching mask film 3 has a single layer structure, it is preferable that chromium content in the etching mask film 3 is 50 atomic% or more, and it is more preferable that it is 60 atomic% or more. In the case where the etching mask film 3 has a multilayer structure, the chromium content of the layer on the side in contact with the resist film 16 is at least 50 atomic% (preferably 60 atomic% or more), and the light shielding film It is preferable to make chromium content of the layer of (2) side less than 50 atomic% (preferably 45 atomic% or less, further 40 atomic% or less). In addition, the etching mask film 3 is in contact with the resist film 16 from the light shielding film 2 side (except for the surface layer in contact with the resist film 16 which cannot avoid a decrease in chromium content due to surface oxidation). It is good also as a composition inclination structure in which chromium content increases toward. In this case, it is less than 50 atomic% (preferably 45 atomic% or less, further 40 atomic% or less) in the place with the smallest chromium content of the etching mask film 3, and 50 atomic% or more in the place with the largest chromium content ( Preferably it is 60 atomic% or more).

The etching mask film 3 preferably has a thickness of 5 nm or more and 20 nm or less. When the film thickness is less than 5 nm, the photoresist in the pattern edge direction of the etching mask film 3 advances before the dry etching of the light shielding film 2 is completed using the etching mask film 3 pattern as a mask, and the light shielding film 2 There is a fear that the CD precision of the design pattern of the pattern transferred to the device may be greatly reduced. On the other hand, when the film thickness is thicker than 20 nm, the film thickness of the resist film 16 necessary for transferring the design pattern to the etching mask film 3 becomes thick, and fine patterns are precisely applied to the etching mask film 3. It becomes difficult to transfer.

By using the manufacturing method of the mask blank 10 of this invention, even when the to-be-coated surface is the etching mask film 3 containing Cr as mentioned above, the resist film 16 with which the defect was reduced can be formed. .

In the manufacturing method of the mask blank 10 of this invention, it is preferable that the thin film 14 which has a to-be-coated surface contains at least Si. Since the wettability of the resist liquid is worse than that of the surface of the thin film 14 containing Si, the surface of the thin film 14 containing Si is made to adhere the resist liquid 26 to the surface of the substrate 15 with the thin film (thin film 14). When dropping on the surface), the resist liquid 26 is particularly easy to bounce off. By using the manufacturing method of the mask blank 10 of this invention, even if the thin film 14 containing silicon is a to-be-coated surface, it can prevent that the resist liquid 26 bounces off the surface of the thin film 14. Therefore, a preferable resist film 16 can be formed.

As a material of the thin film 14 containing Si, MoSi, MoSiO, MoSiN, MoSiON, Si single body, SiO, SiN, SiON, WSi, TaSi, etc. are mentioned, for example.

In the manufacturing method of the mask blank 10 of this invention, the predetermined | prescribed etching selection of the light shielding film 2 and the light shielding film 2 which the thin film 14 which has a to-be-coated surface consist of a metal or a metal compound which can be etched by a fluorine-type dry etching is carried out. It may be a laminated film with the etching mask film 3 of a material having a ratio.

As a light shielding film 2 which consists of a metal or a metal compound which can be etched by fluorine-type dry etching, a silicon containing material is mentioned, for example. In that case, the material containing chromium is mentioned as a material which has a predetermined etching selectivity with this light shielding film 2. As a material containing chromium, the chromium compound containing chromium single substance or 1 or more types chosen from chromium and oxygen, nitrogen, and carbon is mentioned, for example. Moreover, it is preferable that the material does not contain a silicon. Specific examples of the chromium compound include chromium oxide, chromium nitride, chromium nitride, chromium oxide carbide, chromium nitride carbide or chromium oxynitride carbide. It is known that these materials have high resistance to fluorine dry etching.

When the chromium content of the material containing chromium is 50 atomic% or more, especially 60 atomic% or more, the fluorine-based dry etching resistance is good, and sufficient etching selectivity can be imparted to the light shielding film 2 and / or the transparent substrate 11. At the same time, the etching mask film 3 is preferably dry-etched under dry etching conditions containing chlorine and oxygen to form a pattern.

As a material containing chromium, for example, chromium is 50 atomic% or more and 100 atomic% or less, especially 60 atomic% or more and 100 atomic% or less, oxygen is 0 atomic% or more and 50 atomic% or less, especially 0 atomic% or more and 40 atomic% The etching mask film (hereinafter, the nitrogen is 0 atomic% or more and 50 atomic% or less, especially 0 atomic% or more and 40 atomic% or less, carbon is 0 atomic% or more and 20 atomic% or less, particularly 0 atomic% or more and 10 atomic% or less). As 3), it can be set as the film which gives sufficient etching selectivity to the light shielding film 2 and / or a transparent substrate.

By using the manufacturing method of the mask blank 10 of this invention, even when the to-be-coated surface is the etching mask film 3 containing Cr as mentioned above, the resist film 16 with which the defect was reduced can be formed. .

As described above, the method for manufacturing the mask blank 10 of the present invention is a sputtering method for the thin film 14 to be the mask pattern 13 for transferring the transfer target to the main surface of the rectangular substrate 11. The film is formed by a vapor deposition method, a CVD method, or the like, and a resist film 16 is formed on the surface of the thin film 14 of the substrate 15 with a thin film by a resist coating step to manufacture a mask blank 10.

Moreover, the mask blank 10 has the mask pattern 13 formation area in the area | region of the center part in the thin film 14 of the board | substrate 15 with a thin film. In the mask pattern 13 formation region, when the substrate 15 with the thin film is patterned to be a transfer mask 18, a mask pattern 13 for transferring and forming a circuit pattern of a transfer object such as a semiconductor substrate is formed. It is an area to be formed. The mask pattern 13 forming region varies depending on the size of the mask blank 10 and the like. For example, when the mask blank 10 has a size of 152 mm × 152 mm, the thin film of the substrate 15 with a thin film is thin. It is an area of 132 mm x 132 mm of the center part in (14).

According to the present invention, a resist pattern is formed by patterning the resist film 16 of the mask blank 10 manufactured by the method of manufacturing the mask blank 10 described above, and the mask pattern 13 is formed using the resist pattern as a mask. The manufacturing method of the transfer mask 18 is characterized by manufacturing the transfer mask 18.

By performing the resist coating process mentioned above, the resist film 16 is formed in the surface of the thin film 14 of the board | substrate 15 with a thin film shown to FIG. 4A, and it shows in FIG. The mask blank 10 can be manufactured. A resist pattern is formed by drawing and developing a predetermined pattern on the resist film 16 of the mask blank 10, and the thin film 14 (for example, a light shielding film) is dry-etched using the resist pattern as a mask to form a mask pattern. (13) (FIG. 4C) can be formed and the transfer mask 18 can be manufactured.

As mentioned above, although this invention was demonstrated based on the said embodiment, this invention is not limited to this. For example, depending on the manufacturing method of the mask blank 10, the mask blank 10 may be manufactured by directly forming the resist film 16 in the main surface of the square-shaped board | substrate 11. As shown in FIG. Also in this case, in order to form the resist film 16 directly on the main surface of the rectangular substrate 11, the manufacturing method of the present invention including the resist coating step described above can be preferably used.

[Example]

Next, the manufacturing method of the mask blank 10 and the manufacturing method of the transfer mask 18 are demonstrated concretely based on an Example.

(Example 1)

By sputtering on a synthetic quartz glass substrate having a size of 152.4 mm x 152.4 mm, a light shielding film 2 made of a MoSiN film (light shielding layer) and a MoSiN film (surface antireflection layer) and an etching mask film 3 are sequentially formed. This obtained the board | substrate 15 with a thin film. Formation of the light shielding film 2 and the etching mask film 3 was performed as follows specifically ,. In addition, the same thin film was formed also in the mask blank 10 of Example 2, the comparative example 1, and the comparative example 2.

A mixed target of molybdenum (Mo) and silicon (Si) (atomic% ratio Mo: Si = 13) to a sputtering target by using a single-sheet sputtering device on a translucent substrate 11 made of synthetic quartz glass. : 87), in a mixed gas atmosphere of argon and nitrogen, a MoSiN film (lower layer (light shielding layer)) is formed into a film thickness of 47 nm by reactive sputtering (DC sputtering), followed by a Mo / Si target ( A lower layer (film composition ratio Mo: 9.9) was formed by forming a MoSiN film (upper layer (surface antireflection layer)) at a thickness of 13 nm in an atmosphere of a mixed gas of argon and nitrogen using an atomic percentage ratio Mo: Si = 13: 87. ArF excimer laser (wavelength 193 nm) consisting of a lamination of atomic%, Si: 66.1 atomic%, N: 24.0 atomic%) and an upper layer (film composition ratio Mo: 7.5 atomic%, Si: 50.5 atomic%, N: 42.0 atomic%) A dragon light shielding film 2 (total film thickness of 60 nm) was formed. In addition, as for elemental analysis of each layer of the light shielding film 2, the Rutherford backscattering analysis method was used.

Subsequently, the light shielding film 2 was provided, and the substrate 15 with a thin film was subjected to heat treatment (annealing treatment) at 450 ° C. for 30 minutes to reduce the film stress of the light shielding film 2.

Next, the etching mask film 3 was formed on the upper surface of the light shielding film 2. Specifically, in the single-leaf sputtering apparatus, a CrN film (film composition ratio Cr: 75.3 atomic%, N :) by a reactive sputtering (DC sputtering) in a mixed gas atmosphere of argon and nitrogen using a chromium (Cr) target. 24.7 atomic%) was formed into a film thickness of 5 nm. Furthermore, by annealing the etching mask film 3 (CrN film) at a temperature lower than that of the light shielding film 2, the stress of the etching mask film 3 is kept as low as possible without affecting the film stress of the light shielding film 2. (Preferably, the film stress is at zero). By the above procedure, the board | substrate 15 with a thin film of Example 1 was obtained.

Next, the resist liquid 26 was apply | coated rotationally on the board | substrate 15 with a thin film by the resist coating process, and the resist film 16 was formed in the surface of the thin film 14. As shown in FIG. The resist and the solvent contained in the resist liquid 26 used the following.

Resist: Positive type chemically amplified resist FEP171 (manufactured by FUJIFILM Materials)

Solvent: Mixed solvent of PGMEA (propylene glycol monomethyl ether acetate) and PGME (propylene glycol monomethyl ether)

Table 1 shows the dropping of the resist liquid 26 and the rotational speed of the substrate during the resist coating step. "Start time" and "end time" of Table 1 have shown as 0 second when the dropping of the resist liquid was started. In addition, "continuation time" shows the time from the start time to the end time of each process. In addition, the start time and start time of "dropping of a resist liquid" correspond to time t _A and time t _B of FIG. 1, respectively. "S1. Of FIG. The start time of the "rotation acceleration step" corresponds to the time t _X. `` S2. The start time of the "rotational speed maintenance step" corresponds to the time t <sub>Y</sub> in FIG. `` S2. The end time of "rotational speed maintenance step" corresponds to the time t _Z of FIG. The same applies to Tables 2 to 6.

In addition, in the homogenization step S6 and the drying step S7, while the substrate 15 with the thin film is rotating, forced exhaustion is performed continuously continuously, and the substrate 15 with the thin film is formed along the upper surface of the substrate 15 with the thin film. The airflow 34 was generated so that the airflow 34 flows in the outer circumferential direction from the center side of the backplane. Therefore, the liquid condensation of the resist liquid 26 which arises in the outer peripheral part (substrate 11 main surface end part) of the thin film substrate 15 by rotation of the thin film substrate 15 rotates effectively out of the thin film substrate 15. In addition, liquid condensation of the resist liquid 26 generated at the four corners of the thin film substrate 15 and the outer peripheral portion of the thin film substrate 15 can be effectively suppressed from being returned to the center portion of the thin film substrate 15. The thick film region of the resist film 16 formed in the four corners and the peripheral portion of the substrate 15 can be reduced, or the swelling of the film thickness of the region can be reduced (restriction of the thick film).

Subsequently, the substrate 15 with the thin film on which the resist film 16 was formed is conveyed to the heat drying apparatus and the cooling apparatus, and the resist film 16 is dried by performing a predetermined heat drying process to produce a mask blank 10. It was.

The defect inspection was performed with respect to the surface of the light shielding film 2 of the mask blank 10 manufactured as mentioned above using the defect inspection apparatus (M6640 by the lasertec company) of 60 nm sensitivity by a laser interference confocal optical system. . The defects of the defect inspection are shown in Table 7. In addition, defect inspection was performed similarly about the mask blanks of Example 2, 3 and Comparative Examples 1-3.

(Example 2)

The mask blank 10 of Example 2 was produced like Example 1 except having dropped the resist liquid 26 and the rotational speed of the board | substrate in the resist coating process in Example 1 as shown in Table 2. It was. Specifically, in Example 1, the rotational acceleration of the rotational acceleration step S1 was 1000 rpm / second, and in Example 2, it was 500 rpm / second.

(Example 3)

The phase shift which the thin film 14 formed on the board | substrate 11 made with MoSiN was carried out as shown in Table 3 of dripping of the resist liquid 26 and the rotational speed of the board | substrate in the resist coating process in Example 1 The mask blank 10 of Example 3 was produced like Example 1 except having been the film, the predetermined light shielding film 2, and the etching mask film 3 which consists of MoSiON. In addition, the predetermined light shielding film 2 is a light shielding film 2 including three layers of a back anti-reflection layer made of CrOCN, a light shielding layer made of CrN, and an antireflection layer made of CrOCN. In addition, in Example 3, dropping of the resist liquid was performed during the rotation acceleration stage, and the rotation acceleration of the substrate 15 with the thin film at this time was 125 rpm / second. In Example 3, the rest step S3 and the free rotation steps S4 and S5 were not performed.

Formation of the phase shift film, the light shielding film 2, and the etching mask film 3 of Example 3 was specifically performed as follows. In addition, the same thin film was formed also in the mask blank 10 of the comparative example 3. As shown in FIG.

Using a DC magnetron sputtering device on a translucent substrate 11 made of quartz glass, using a mixed target containing Mo and Si (Mo content relative to the total content of Mo and Si is 9.5%) as a sputtering target, In a mixed gas atmosphere of argon, nitrogen, and helium (Ar: 9 sccm, N ₂ = 81 sccm, He: 76 sccm), reactive sputtering with power of 2.8 kW is performed to form a phase shift film made of MoSiN having a thickness of 69 nm. It was. In addition, this phase shift film has a transmittance of 6% and a phase shift amount of approximately 180 degrees in an ArF excimer laser (wavelength 193 nm).

Subsequently, using a DC magnetron sputtering device on the phase shift film, and using a chromium target for the sputtering target, a mixed gas atmosphere of argon, carbon dioxide, nitrogen, and helium (Ar: 20 sccm, CO ₂ : 35 sccm, N ₂ : 5 sccm, He: 30 sccm), reactive sputtering with a power of 1.5 kW was performed to form a back anti-reflection layer made of CrOCN having a thickness of 30 nm.

Subsequently, using a chromium target, in a mixed gas atmosphere (Ar: 25 sccm, N ₂ : 5 sccm) of argon and nitrogen, reactive sputtering with power of 1.7 kW was performed to form a light shielding layer made of CrN having a thickness of 4 nm. It was.

Then, using a chromium target, power of 1.7 kW in a mixed gas atmosphere of argon, carbon dioxide, nitrogen, and helium (Ar: 20 sccm, CO ₂ : 35 sccm, N ₂ = 10 sccm, He: 30 sccm) By sputtering, an antireflection layer made of CrOCN having a thickness of 14 nm was formed. Thus, the light shielding film 2 which consists of a back surface antireflective layer, a light shielding layer, and an antireflective layer whose total film thickness is 48 nm was formed.

Subsequently, an etching mask film 3 made of SiON was formed on the light shielding film 2. Specifically, by using a Si target as a sputtering target, a reactive sputtering of 1.8 kW of electric power is performed in a mixed gas atmosphere (Ar: 8 sccm, NO = 29 sccm, He: 32 sccm) of argon, nitrogen monoxide, and helium. And an etching mask film 3 made of SiON having a thickness of 15 nm was formed to obtain a substrate 15 with a thin film of Example 3.

(Example 4)

The dropping of the resist liquid 26 and the rotational speed of the substrate during the resist coating step in Example 1 were as shown in Table 4. In Example 4, the initial rotation step S0 was carried out, and the dropping of the resist liquid was performed during the rotation acceleration step S1. The rotational acceleration of the thin film substrate 15 at this time was 125 rpm / second. In Example 4, the rest step S3 and the free rotation steps S4 and S5 were not performed.

(Example 5)

The dropping of the resist liquid and the rotational speed of the substrate during the resist coating step in Example 3 were as shown in Table 5. In addition, in Example 5, initial stage rotation S0 was performed and the addition of the resist liquid was performed at the time of rotation acceleration stage S1. The rotational acceleration of the thin film unit substrate 15 at this time was 50 rpm / second. In Example 5, the rest step S3 and the free rotation steps S4 and S5 were performed.

(Comparative Example 1)

The mask blank 10 of Comparative Example 1 was prepared in the same manner as in Example 1 except that the dropping of the resist liquid 26 and the rotational speed of the substrate during the resist coating step in Example 1 were as shown in Table 4. It was. In addition, in the comparative example 1, dripping of the resist liquid 26 was performed in the state which rotation of the board | substrate 11 stopped, and the rest process (S3) was performed after that for 2 second. In Comparative Example 1, the rotational acceleration step S1 and the rotational speed maintenance step S2 were not performed.

(Comparative Example 2)

The mask blank 10 of Comparative Example 2 was produced in the same manner as in Example 1 except that the dropping of the resist liquid 26 and the rotational speed of the substrate during the resist coating step in Example 1 were as shown in Table 5. It was. In addition, in the comparative example 2, acceleration in rotation acceleration step S1 was made into 0.05 second by rotation acceleration 20000 rpm / sec.

(Comparative Example 3)

The mask blank 10 of Comparative Example 3 was produced in the same manner as in Example 3 except that the dropping of the resist liquid 26 and the rotational speed of the substrate in the resist coating step in Example 3 were as shown in Table 6. . In Comparative Example 3, an initial rotation step S0 that rotates at a rotational speed of 700 rpm for 2 seconds to 2 seconds, that is, from -2 seconds to 0 seconds before the dropping start time (0 seconds) of the resist liquid 26 is performed. Installed. Therefore, the rotational speed of the substrate at the start of dropwise addition of the resist liquid 26 was 700 rpm. In Comparative Example 3, the resting step S3 and the free rotation step (acceleration) S4 were not performed.

(Defect Number of Mask Blanks 10 of Examples and Comparative Examples)

As shown in Table 9, in the mask blanks 10 of Examples 1 to 5 of the present invention, the number of defects after the formation of the resist film 16 was significantly reduced compared with the mask blanks 10 of Comparative Examples 1 to 3. FIG.

In Example 1, since the rotational acceleration step S1 was fast for 1 second (1000 rpm / sec), the result was that the micro defects were slightly increased. From this, it is considered that the rotational acceleration of the rotational acceleration step S1 is preferably 1000 rpm / second or less. In addition, in Example 4, since the rotational speed was already higher at 500 rpm in the dropping start step S0 of the dropping step, a small number of minute defects appeared. In Example 5, although the number of defects was small, time was required for the rotational speed maintaining step S2 in order to obtain film thickness uniformity.

In the comparative example 1, since the resist liquid 26 was not dripped at the rotation acceleration step S1, in order to reduce the number of defects after the formation of the resist film 16, the resist liquid was dropped at the rotation acceleration step S1. I can say that I need to

In the comparative example 2, since rotation acceleration step S1 was 0.05 second and a short time, it is guessed that rotation acceleration step S1 is required for at least 0.1 second or more. In the comparative example 3, since the rotation speed of the thin film board | substrate 15 at the start of dropping of the resist liquid 26 was 700 rpm, the rotation speed of the thin film board | substrate 15 at the start of dripping needs to be less than 700 rpm. I guess that.

(Experimental Example)

Comparative experiments were performed in which a resist layer was formed under the conditions of Example 3 (Experimental Example 1) and Comparative Example 3 (Experimental Example 2) by combining the test solutions 1 to 5 with different amounts of the surfactants having similar compositions to the resist liquid. It was done. The test solution melt | dissolved and combined 100 mass parts of alkali soluble novolak resin of molecular weight Mv5000 in 780 weight part of mixed solvents of PGMEA and PGME. As the surfactant, a fluorine-silicone-based surfactant was used. The addition amount of surfactant is added in the ratio of 0-1.0 mass part with respect to 100 mass parts of novolak resin, The addition amount of the test liquid 1 is 0, The addition amount of the test liquid 2 is 0.2, The addition amount of the test liquid 3 is 0.4, The addition amount of the test liquid 5 The addition amount of 0.8 and the test liquid 6 was 1.0. Evaluation was performed by the same method as the Example.

When applying by the method of gradually increasing rotation speed in rotation acceleration step S1 like Experimental example 1, even if surfactant was not contained, it turned out that the coating defect by foam is few. From this, when it applied by the method of gradually increasing rotation speed, it turned out that even the resist liquid with a small amount of surfactant addition can spread to a board | substrate. On the other hand, if the addition amount of the surfactant is already small at the rotational speed of 700 rpm at the start of resist dropping as in Experimental Example 2, it is considered that the test solution does not spread well and defects due to bubbles are generated.

2:
3: etching mask film
10: mask blank
11: substrate
12: pattern line
13: mask pattern
14: thin film
15: substrate with thin film
16: resist film
18: transfer mask
20: rotary coating device
21: spinner chuck
22: Nozzle
23: cup
24: inner ring
26: resist liquid
30: exhaust means
32: opening
34: airflow

Claims (15)

A method for producing a mask blank comprising a resist coating step for forming a resist film made of a resist material on a substrate,
The resist coating step,
A dripping step for dripping a resist liquid containing a resist material and a solvent on the square substrate;
Dropping process,
When the rotational speed of the substrate at time t is R (t), when the dropping start time of the resist liquid is t _A and the dropping end time of the resist liquid is t _B , the time of t _A ≤ t ≤ t _B In the range,
(1) the relationship between R (t _A ) <R (t _B ),
(2) for from t _A to reach the R (t _B), t ₁ relationship, R (t ₁₎ ≤R (t ₂₎ relative to <t ₂ in a certain time t ₁ and t ₂ and ,
(3) the relationship between 0 ≦ R (t _A ) <700 rpm,
(4) The relationship from t _A to R (t _B ) is 0.1 seconds or more
And varying the rotational speed R (t) of the substrate so as to satisfy the following requirements. The method of claim 1,
In relation to (2), t ₁ <t ₂ is that for any time t ₁ and t ₂ of, R (t ₁₎ relationship, the method of producing a mask blank <R (t _2). 3. The method of claim 2,
And the rotational acceleration dR (t) / dt is constant. The method of claim 1,
When the rotational speed R (t) of the substrate changes in the time range from t _A to R (t _B ), the rotational acceleration dR (t) / dt which is the acceleration of the rotational speed R (t) is 10. The manufacturing method of the mask blank whose rpm / s <= dR (t) / dt <1000 rpm / s. 5. The method according to any one of claims 1 to 4,
The dropping process,
a rotation acceleration step of accelerating the rotational speed R (t) of the substrate in a time range of t _A ≤ t ≤ t _Y ;
_Y t <time in the range of t≤t _Z, the rotational speed R (t) is a constant rotation speed of the substrate holding stage
Lt; / RTI &gt;
The relationship between the time t _Y at which the rotational speed maintaining step is started and the dripping end time t _B of the resist liquid is t _Y ≦ t _B ,
The rotational speed R (t) (t _Y <t≤t _Z ) of the rotational speed maintaining step is R (t) ≥ 300 rpm,
The rotational acceleration dR (t) / dt (t _A ≤t≤t _Y ) in the rotational acceleration step satisfies 10 rpm / s ≤ dR (t) / dt ≤ 1000 rpm / s, and at a constant rotational acceleration And the rotational speed of the substrate is accelerated. 6. The method of claim 5,
And the rotational speed R (t) (t _Y <t ≦ t _Z ) of the substrate in the rotational speed maintaining step is 500 rpm ≦ R (t) ≦ 1000 rpm. 7. The method according to any one of claims 1 to 6,
The method for producing a mask blank, wherein the resist coating step further includes a step of lowering the rotational speed of the substrate or stopping the rotation following the dropping step. 8. The method according to any one of claims 1 to 7,
The resist film forming process, after the dropping step, R (t _B) than the method of producing a mask blank comprising a uniform step of rotating the substrate at a rotational speed of the fast substrate. 9. The method of claim 8,
The manufacturing method of the mask blank which includes the free rotation process which raises a rotation speed step by step toward the high speed rotation speed of a homogenization process between the said pause process and a homogenization process. 10. The method according to claim 8 or 9,
Operating a venting means for venting to produce an airflow directed toward the substrate in a homogenizing step. 11. The method according to any one of claims 1 to 10,
The surface for forming the resist film of the substrate is the surface of the thin film formed by the reactive sputtering method, and the thin film contains at least one element selected from the group consisting of at least Cr, Ta, Si, Mo, Ti, V, Nb and W. The manufacturing method of the mask blank containing. 12. The method of claim 11,
The said thin film contains at least Cr, and the ratio of Cr contained in the said thin film is the manufacturing method of the mask blank at least 50 atomic% or more. 12. The method of claim 11,
And the thin film comprises at least Si. The method according to any one of claims 1 to 13,
A method for producing a mask blank, wherein the resist liquid contains substantially no surfactant. A resist pattern is formed by patterning the resist film of the mask blank manufactured by the method for producing a mask blank according to any one of claims 1 to 14, and a mask pattern is formed using the resist pattern as a mask for transfer. The manufacturing method of the transfer mask characterized by manufacturing a mask.

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