JP6316861B2 - Method for starting film forming apparatus, method for manufacturing mask blank, method for manufacturing transfer mask, and method for manufacturing semiconductor device - Google Patents

Description

  The present invention mainly relates to a method for starting a film forming apparatus used for manufacturing a mask blank. The present invention also relates to a method of manufacturing a mask blank using the film forming apparatus started up by the above-described start-up method. The present invention also relates to a method for manufacturing a phase shift mask manufactured using the mask blank and a method for manufacturing a semiconductor device using the phase shift mask.

  Generally, in a semiconductor device manufacturing process, a fine pattern is formed using a photolithography method. Also, a number of transfer masks are usually used for forming this fine pattern. When miniaturizing a semiconductor device pattern, it is necessary to shorten the wavelength of an exposure light source used in photolithography in addition to miniaturization of a mask pattern formed on a transfer mask. In recent years, the exposure light source used in the manufacture of semiconductor devices has been shortened from a KrF excimer laser (wavelength 248 nm) to an ArF excimer laser (wavelength 193 nm).

  A mask blank serving as an original for producing a transfer mask includes at least a thin film for forming a transfer pattern on a substrate. The thin film of the mask blank is generally formed by a film forming apparatus using a sputtering method. Patent Document 1 discloses a DC magnetron sputtering apparatus used for manufacturing a mask blank. In this sputtering apparatus, a sputtering target and a substrate holder are arranged inside a vacuum chamber. In addition, this sputtering apparatus is provided with a shield which is a removable film adhesion prevention part on the inner wall side of the vacuum chamber.

  As disclosed in Patent Document 2, the shield of the sputtering apparatus (film forming apparatus) has a configuration in which a plurality of members are combined, and the shielding particles adhere to the inner wall of the vacuum chamber. Is preventing. Moreover, the labyrinth-shaped ventilation path is provided in the connection part of the several shield member. By having this air passage, it becomes possible for an inert gas (such as argon) or a reactive gas (such as oxygen or nitrogen) flowing into the processing chamber from the outside to enter the internal space surrounded by the shield. ing.

Japanese Patent Laying-Open No. 2005-200682 International Publication No. 2010/061603

  When the process of forming a thin film on the substrate (hereinafter referred to as a thin film forming process) is repeated with the film forming apparatus using the sputtering method as described above, the sputtered particles from the target take in the reactive gas into the inner wall of the shield. Accumulate. In other words, an adhesion film of the same constituent elements as the thin film formed on the translucent substrate is formed on the inner wall of the shield, and the thickness of the adhesion film gradually increases. The adhesion film itself has a relatively strong internal stress. As the thickness of the adhesion film increases, the force (tensile force or compression force) applied to the adhesion film due to internal stress increases. When the attached film cannot resist the force, the attached film is cracked and detached from the shield. A part of the detached adhesion film adheres to the thin film being formed on the substrate and becomes a cause of generation of defects. For this reason, the shield is generally replaced when a predetermined film formation cycle is reached.

  The shield of the film forming apparatus is generally formed of a metal material that is a material that is difficult to be charged, and aluminum or the like is often used. In addition, a new shield immediately after replacement or a new shield immediately after introducing a new film forming apparatus has a surface in which the metal material is exposed. When the thin film formation process is performed with the surface state of such a shield, a thin film for pattern formation formed on the substrate is ejected by a part of sputtered particles etc. colliding with the surface of the shield, and the shield metal atoms are ejected. There is a risk of being taken in by the material constituting the. For this reason, before performing a thin film formation process, a process of forming a deposited film by causing particles to jump out of a target by a sputtering method and adhere to a surface on the inner space side of a new shield (hereinafter referred to as a shield inner wall surface). (Aging process) is performed.

  This aging process is often performed in addition to the purpose of coating the inner wall surface of the shield, and also for the purpose of bringing the surface state of the target closer to the surface state during the thin film formation step. In this case, in the first aging process, only a noble gas (such as argon) having high sputtering efficiency is introduced into the film forming chamber, and the atoms constituting the target surface are caused to collide with the noble gas plasma against the target surface. Clean the surface of the target by flipping it off. At this time, many of the atoms jumping out from the surface of the target are deposited on the inner wall surface of the shield to form a lowermost deposited film.

  In the next aging process, reactive sputtering is performed under substantially the same film formation conditions as in the thin film formation process (the flow rates of the noble gas and reactive gas flowing into the film formation chamber, the internal pressure, the voltage applied to the target, etc.). . This aging process makes the surface of the target almost the same as in the thin film formation process, and has the same composition as the pattern forming thin film formed on the substrate in the thin film formation process on the lowermost deposited film on the inner wall surface of the shield. The deposited film is formed.

  A thin film forming process in which a film forming apparatus is set up by the aging process as described above, and a single substrate is placed on a substrate stage, and a thin film for pattern formation is formed on the substrate by a reactive sputtering method. Even if the process is repeated, it is possible to reduce variations in physical properties such as composition and optical characteristics between the pattern forming thin film first formed on the substrate and the pattern forming thin film formed on the substrate thereafter. it can.

  Conventionally, when the thin film forming process is started with the film forming apparatus after the aging process, the defect generation ratio of the pattern forming thin film tends to increase as the number of substrates having the pattern forming thin film increases. is there. For this reason, every time the number of manufactured sheets reaches a predetermined number, the shield is replaced and an aging process is performed to start up the film forming apparatus. However, depending on the film forming conditions of the pattern forming thin film formed by the film forming apparatus in this thin film forming process, it has been found that the defect generation rate of the pattern forming thin film becomes high at a small number of manufacturing stages. . This problem cannot be solved simply by advancing the shield replacement time. In particular, although the details will be described later, it has been found that this problem becomes prominent when a thin film for pattern formation having an indentation hardness of less than 5000 MPa, which is derived by a nanoindentation method, is formed by a film forming apparatus.

  The present invention has been made in order to solve the above-described conventional problems, and in the start-up method of the film forming apparatus, a sputtering method is used on the substrate by using the film forming apparatus started up by the start-up method. Even when a thin film for pattern formation consisting of a material containing an element derived from a transition metal, silicon and a reactive gas and having an indentation hardness of less than 5000 MPa derived by a nanoindentation method is used for the pattern formation An object of the present invention is to provide a method for starting up a film forming apparatus that can greatly reduce the number of detected defects in a thin film.

  Further, the present invention comprises a material containing an element derived from a transition metal, silicon, and a reactive gas on a substrate by sputtering using a film forming apparatus, and the indentation hardness derived by the nanoindentation method is less than 5000 MPa. An object of the present invention is to provide a mask blank manufacturing method in which the number of detected defects in the pattern forming thin film is greatly reduced even when a mask blank is manufactured by forming a pattern forming thin film. . Furthermore, it aims at providing the method of manufacturing the transfer mask using such a mask blank. An object of the present invention is to provide a method of manufacturing a semiconductor device using such a transfer mask.

In order to achieve the above object, the present invention has the following configuration.
(Configuration 1)
A method of starting a film forming apparatus provided with a target and a shield made of a material containing a transition metal and silicon in a film forming chamber,
Introducing a noble gas and a reactive gas into the film forming chamber, and comprising a material containing the transition metal, silicon and the element derived from the reactive gas on the surface of the shield by reactive sputtering, and by a nanoindentation method Forming a lower layer film having an indentation hardness of 5000 MPa or more,
A noble gas and a reactive gas are introduced into the film forming chamber, and a nanoindentation made of a material containing the transition metal, silicon and the element derived from the reactive gas on the lower layer film of the shield by reactive sputtering. And a step of forming an upper film whose indentation hardness is less than 5000 MPa, which is derived by the method.

(Configuration 2)
2. The method of starting a film forming apparatus according to Configuration 1, wherein the noble gas is a mixed gas of at least one gas selected from argon, krypton, and xenon and helium.

(Configuration 3)
The ratio obtained by dividing the flow rate per unit time of helium gas in the noble gas introduced into the film forming chamber in the step of forming the lower layer film by the total flow rate per unit time of the noble gas forms the upper layer film. 3. The configuration 2 according to claim 2, wherein a ratio obtained by dividing a flow rate per unit time of the helium gas in the noble gas introduced into the film forming chamber in the step of dividing by a total flow rate per unit time of the noble gas is greater A method for starting a film forming apparatus.

(Configuration 4)
4. The film-forming apparatus according to claim 1, wherein the reactive gas in the step of forming the lower layer film and the step of forming the upper layer film includes at least a gas containing nitrogen. How to raise.

(Configuration 5)
The ratio of the content of the transition metal divided by the total content of the transition metal and silicon in the target is less than 34%. How to raise.

(Configuration 6)
A method for manufacturing a mask blank using a film forming apparatus after being started up by the method for starting a film forming apparatus according to any one of configurations 1 to 5,
The mask blank comprises at least a pattern forming thin film on a substrate,
The substrate is set on a substrate stage provided in the film forming apparatus after the start-up, a noble gas and a reactive gas are introduced into the film forming chamber, and the main surface of the substrate is formed by reactive sputtering. Comprising a step of forming a thin film for pattern formation comprising a material containing an element derived from the transition metal, silicon and the reactive gas and having an indentation hardness of less than 5000 MPa derived by a nanoindentation method. A method for manufacturing a mask blank.

(Configuration 7)
In the film forming chamber, a mask blank manufacturing method using a film forming apparatus including a target made of a material containing a transition metal and silicon, a shield, and a substrate stage,
The mask blank comprises at least a pattern forming thin film on a substrate,
Introducing a noble gas and a reactive gas into the film forming chamber, and comprising a material containing the transition metal, silicon and the element derived from the reactive gas on the surface of the shield by reactive sputtering, and by a nanoindentation method Forming a lower layer film having an indentation hardness of 5000 MPa or more,
The substrate is placed on a substrate stage in the film forming chamber, a noble gas and a reactive gas are introduced into the film forming chamber, and the transition metal, silicon, and the reaction are formed on the main surface of the substrate by reactive sputtering. And a step of forming a pattern-forming thin film having an indentation hardness of less than 5000 MPa, which is made of a material containing an element derived from a property gas and derived by a nanoindentation method.

(Configuration 8)
8. The mask blank according to claim 7, wherein in the step of forming the pattern forming thin film, a deposited film made of the same material as that constituting the pattern forming thin film is also formed on the lower layer film of the shield. Manufacturing method.

(Configuration 9)
9. The method of manufacturing a mask blank according to Configuration 7 or 8, wherein the noble gas is a mixed gas of at least one gas selected from argon, krypton, and xenon and helium.

(Configuration 10)
The ratio obtained by dividing the flow rate per unit time of the helium gas in the noble gas introduced into the film forming chamber in the step of forming the lower layer film by the total flow rate per unit time of the noble gas is the thin film for pattern formation The ratio of the flow rate per unit time of the helium gas in the noble gas introduced into the film forming chamber in the step of forming the gas is larger than the ratio obtained by dividing the total flow rate per unit time of the noble gas. The manufacturing method of the mask blank of description.

(Configuration 11)
11. The mask blank according to claim 7, wherein the reactive gas in the step of forming the lower layer film and the step of forming the pattern forming thin film includes at least a gas containing nitrogen. Production method.

(Configuration 12)
The ratio of the content of the transition metal divided by the total content of the transition metal and silicon in the target is less than 34%, The method for manufacturing a mask blank according to any one of configurations 7 to 11 .

(Configuration 13)
A transfer mask comprising a step of forming a transfer pattern on the pattern forming thin film by dry etching using a mask blank manufactured by the mask blank manufacturing method according to any one of Structures 6 to 12 Production method.

(Configuration 14)
A method for manufacturing a semiconductor device, comprising: a step of exposing and transferring a transfer pattern onto a resist film on a semiconductor substrate using the transfer mask manufactured by the method for manufacturing a transfer mask according to Structure 13.

  According to the start-up method of the film forming apparatus of the present invention, the transition metal, silicon, and the element derived from the reactive gas are contained on the substrate by the sputtering method using the film forming apparatus set up by the start-up method. Even when a pattern forming thin film made of a material and having an indentation hardness of less than 5000 MPa, which is derived by a nanoindentation method, the number of detected defects in the pattern forming thin film can be greatly reduced. . Further, according to the mask blank manufacturing method of the present invention, the substrate is made of a material containing an element derived from a transition metal, silicon and a reactive gas on the substrate by a sputtering method using a film forming apparatus, and is formed by a nanoindentation method. Even in the case of manufacturing a mask blank by forming a pattern forming thin film having an indentation hardness of less than 5000 MPa, the number of detected defects in the pattern forming thin film can be greatly reduced.

It is a schematic diagram which shows an example of the film-forming apparatus in embodiment of this invention. It is a graph which shows the relationship between the nitrogen gas flow rate at the time of sputtering in an Example, and the indentation hardness of the formed thin film. It is a graph which shows the relationship between the nitrogen gas flow rate at the time of sputtering in an Example, and the Young's modulus of the formed thin film. It is a graph which shows the relationship between the helium gas flow rate at the time of sputtering in an Example, and the indentation hardness of the formed thin film. It is a graph which shows the relationship between the helium gas flow rate at the time of sputtering in an Example, and the Young's modulus of the formed thin film.

  Each embodiment of the present invention will be described below. First, the background to the present invention will be described. In the mask blank manufacturing process, a pattern forming thin film containing an element derived from a reactive gas such as transition metal, silicon and nitrogen is formed on a substrate by reactive sputtering using a film forming apparatus. Yes. The conditions for various characteristics such as optical characteristics and etching characteristics required for the pattern forming thin film of the mask blank vary depending on the characteristics required for the transfer mask manufactured from the mask blank. The reactive sputtering conditions (film forming conditions) when the pattern forming thin film is formed on the substrate by the film forming apparatus vary depending on various characteristics required for the pattern forming thin film.

  On the other hand, the size and number of defects allowed in the thin film for pattern formation of the mask blank differ depending on the grade such as accuracy required for a transfer mask manufactured from the mask blank. There are various factors that cause defects in the thin film for pattern formation. When the thin film is formed by reactive sputtering in the film forming apparatus, the attached film drops off from the inner wall surface of the shield and adheres to the thin film in many cases. When a thin film is formed by a sputtering method using a material containing an element derived from a reactive gas such as transition metal, silicon and nitrogen (hereinafter also simply referred to as a transition metal silicide compound material), There is a tendency that defects due to dropout are likely to occur.

  Therefore, an attempt was made to verify the tendency of the film formation conditions when forming a thin film of a transition metal silicide compound material by reactive sputtering and the number of defects detected in the formed thin film. However, the variation parameters of the film formation conditions when forming a thin film of a transition metal silicide compound material by reactive sputtering are various. Even the variation parameters related to the deposition gas can at least include the type, number and flow rate of each precious gas introduced into the deposition chamber, the type, number and flow rate of each reactive gas, and the gas pressure in the deposition chamber. it can. In addition to this, there are also parameters of fluctuations in voltage and current applied to the target (cathode). Furthermore, when a thin film of a transition metal silicide compound material is formed by reactive sputtering, since a mixed target of transition metal and silicon is used, a variation parameter of the mixing ratio of the transition metal and silicon of the target material is also mentioned. For this reason, even if it is possible to collect individual film formation conditions when forming each thin film of transition metal silicide compound material that tends to have a large number of defects, the overall trend can be grasped only by the film formation conditions. It was difficult.

  Therefore, the physical property value of the thin film of transition metal silicide compound material formed on the substrate by reactive sputtering is measured, and it is verified whether there is a correlation between the physical property value of the thin film and the number of defects detected in the thin film. went. As a result, there is a clear correlation between the indentation hardness (hereinafter, also simply referred to as indentation hardness) derived by performing nanoindentation on the thin film and the number of defects detected in the thin film. I found out. Specifically, it was found that when the indentation hardness of the thin film is less than 5000 MPa, the number of defects detected in the thin film tends to increase greatly. It can be said that the indentation hardness of the thin film formed on the substrate is almost the same as the indentation hardness of the film attached to the inner wall surface of the shield when the thin film is formed by reactive sputtering.

  There is a correlation between the indentation hardness of the film adhering to the inner wall surface of the shield when reactive sputtering is performed in the film deposition system and the number of defects in the thin film formed on the substrate. It is presumed to be caused by the mechanism. Generally, a metal material such as aluminum is used for the shield material. When reactive sputtering is performed in the film forming apparatus, plasma is generated in the inner region surrounded by the shield. At this time, the temperature of the shield also rises, and accordingly the shield undergoes thermal expansion. The temperature of the deposited film of the transition metal silicide compound material adhering to the inner wall surface of the shield also rises and causes thermal expansion. On the other hand, when plasma is not generated in the deposition chamber, the temperature of the shield decreases. The thermal expansion coefficient of the transition metal silicide compound material is significantly smaller than the thermal expansion coefficient of a metal material such as aluminum. For this reason, when the temperature of the shield rises and falls, a relatively large difference occurs in the expansion / contraction difference between the shield and the attached film. On the other hand, transition metal silicide compound material thin films tend to be less malleable than metal material thin films.

  Due to these factors, when the temperature of the shield rises and falls, the tensile force and compression caused by the difference in expansion and contraction between the shield and the transition metal silicide compound material adhering to the inner wall surface of the shield The force works, and it cannot resist the force, and the adhered film causes brittle fracture and generates dust. In addition, the adhesion force between the shield and the adhesion film cannot resist the force, and a part of the adhesion film falls off the shield. Substances generated from the adhered film and a part of the adhered film fall off adhere to the surface of the substrate set on the substrate stage or the surface of the thin film formed on the substrate, and these become defects of the thin film.

  When the thin film formed on the substrate with the film forming apparatus has an indentation hardness of 5000 MPa or more, the indentation hardness of the attached film adhering to the inner wall surface of the shield becomes 5000 MPa or more even if the conventional aging process is applied. The occurrence frequency of dust generation from the adhered film and dropping off of the adhered film can be kept low. However, when the thin film formed on the substrate with the film forming apparatus has an indentation hardness of less than 5000 MPa, when the conventional aging process is applied, the indentation hardness of the attached film adhering to the shield inner wall surface becomes less than 5000 MPa, It is difficult to avoid a large amount of dust generation from the adhesion film and dropping off of the adhesion film.

[First Embodiment]
As a result of these considerations, when a thin film having an indentation hardness of less than 5000 MPa is formed on a substrate by sputtering in the film forming apparatus, the aging process is divided into the following two processes to start up the film forming apparatus I came to the conclusion that it should be. That is, the first embodiment of the present invention is a method for starting up a film forming apparatus provided with a target and a shield made of a material containing a transition metal and silicon in a film forming chamber. An underlayer film having an indentation hardness of 5000 MPa or more derived from a material containing transition metal, silicon, and an element derived from reactive gas on the inner wall surface of the shield by introducing reactive gas and reactive sputtering. A material containing a transition metal, silicon, and an element derived from a reactive gas on a lower layer film formed on the inner wall surface of the shield by reactive sputtering, by introducing a noble gas and a reactive gas into the film forming chamber An upper layer film having an indentation hardness of less than 5000 MPa, which is derived by a nanoindentation method. Is characterized in that a step of.

  By attaching a lower layer film having an indentation hardness of 5000 MPa or more on the inner wall surface of the shield, it is possible to increase resistance to tensile force and compressive force applied to the lower layer film due to expansion / contraction difference between the shield and the temperature change. It is possible to suppress the lower layer film from causing brittle fracture or dropping. In addition, even if an upper layer film having an indentation hardness of less than 5000 MPa adheres to the lower layer film, the upper layer film directly receives the tensile force and the compressive force generated by the expansion and contraction with the shield. The tensile force and compressive force applied to the are reduced. The lower layer film and the upper layer film are formed of the same transition metal and silicon-containing material. For this reason, the interface between the lower layer film and the upper layer film is in a chemically bonded state, and the adhesion force between the lower layer film and the upper layer film is much greater than when the upper layer film is directly attached to the shield inner wall surface. high. By combining these actions, it is possible to significantly suppress the upper layer film from causing brittle fracture or falling off.

  The detailed configuration of the present invention described above will be described below. FIG. 1 is a schematic diagram of a film forming apparatus according to the first embodiment of the present invention. The film forming apparatus 1 is for forming a pattern forming thin film on a main surface of a substrate 100 by reactive sputtering. The film formation apparatus 1 includes a film formation chamber 2, a substrate stage 3, a cathode 4, a gas inflow portion 5, a gas discharge portion 6, a lower shield 71 and an upper shield 72 (hereinafter, the lower shield 71 and the upper shield 72 are combined. And also referred to as shield 7). The substrate stage 3 on which the substrate 100 is installed is provided in a state where the rotation shaft 31 penetrates the lower wall side of the film forming chamber 2. The cathode 4 is provided in a state of penetrating the upper wall of the film forming chamber 2. A target 9 is attached to the cathode 4 via a backing plate 8. In addition, a shield 7 is provided to prevent the sputtered particles that have jumped out of the target 9 from adhering to the inner wall surface of the film forming chamber 2 when sputtering is performed by the film forming apparatus 1.

  A mixed gas of noble gas and reactive gas, which is a film forming gas, is introduced into the film forming chamber 2 from the gas inflow portion 5. Then, the film forming gas in the film forming chamber 2 is discharged from the gas discharge unit 6. The gas discharge unit 6 is also used when the film forming chamber 2 is evacuated to a predetermined degree of vacuum. The gas inflow portion 5 may have a configuration in which a plurality of inflow portions are provided in the film formation chamber 2. For example, the gas inflow part 5 may be provided in the film formation chamber 2 with an inflow part for inflow of noble gas and an inflow part for inflow of reactive gas, or the inflow part may be provided for each gas type. 2 may be provided.

  Each tip portion (connecting portion) of the lower shield 71 and the upper shield 72 has a concave shape in cross section. The lower shield 71 and the upper shield 72 are fitted into the film forming chamber 2 with a space left between the concave portions. A structure that leaves such a space is called a labyrinth structure. An inner region (hereinafter referred to as a shield inner region) surrounded by inner walls of the lower shield 71 and the upper shield 72 of the film forming chamber 2 and an outer region of the lower shield 71 and the upper shield 72 (hereinafter referred to as the shield inner region). Hereinafter, the film forming gas between the outer region and the shield outside region flows in and out through the labyrinth structure. The shield 7 is preferably formed of a material having the largest number of metals among the elements constituting the material, and more preferably formed of a metal material. More preferably, the shield 7 is made of aluminum, iron, copper or the like.

  It is preferable that the inner wall surface of the shield 7 has a predetermined surface roughness (small unevenness) by performing a sandblasting process or the like. Since the inner wall surface of the shield 7 has a predetermined surface roughness, a lower layer film directly attached to the inner wall surface (in the case of a structure in which a lowermost layer film is formed between the shield 7 and the lower layer film described below, It can be expected that the adhesion of the lower layer film) to the shield 7 is improved by the anchor effect. The predetermined surface roughness is, for example, preferably 5 μm or more, more preferably 6 μm or more in arithmetic average roughness Ra.

  As the cathode 4, either a DC power supply method or an RF power supply method can be applied. That is, the start-up method of the film forming apparatus according to the first embodiment can be applied to either a DC sputtering film forming apparatus or an RF sputtering film forming apparatus. If the film forming apparatus is of a sputtering system in which plasma exists in the shield inner region during aging (sputtering) and the shield causes a relatively large thermal expansion and contraction, the method for starting the film forming apparatus of the first embodiment is applied. The effect by this is acquired.

  In the method for starting up the film forming apparatus of the first embodiment, the thin film for pattern formation formed on the main surface of the substrate 100 using the film forming apparatus 1 after the start-up is derived from a transition metal, silicon, and a reactive gas. It is particularly effective when applied when it is made of a material containing an element and the indentation hardness is less than 5000 MPa. This is because in the aging process in starting up the film forming apparatus 1, it is required to perform reactive sputtering under substantially the same film forming conditions when forming the pattern forming thin film. In this case, the film adhering to the inner wall surface of the shield during the aging process tends to cause dust generation or film peeling (dropping from the shield) due to brittle fracture due to thermal expansion and contraction of the shield.

  In the method for starting up the film forming apparatus of the first embodiment, a noble gas and a reactive gas are introduced into the film forming chamber 2, a voltage is applied to a target made of a material containing a transition metal and silicon, and reactive sputtering is performed. It is characterized in that the aging process for causing the aging is performed in at least two stages: a process of forming a lower layer film on the inner wall surface of the shield 7 and a process of forming an upper film. The lower layer film previously formed on the inner wall surface of the shield is made of a material derived from a transition metal, silicon and a reactive gas, and has an indentation hardness of 5000 MPa or more. The indentation hardness of this lower layer film is more preferably 5500 MPa or more, and further preferably 6000 MPa or more. This is because the lower the film having a higher indentation hardness, the higher the resistance of the shield to thermal expansion and contraction.

  In addition, indentation hardness in this specification is hardness measured using the principle of the nanoindentation method established by ISO14577. More specifically, a special probe equipped with a diamond indenter is pushed from the surface of the thin film with an atomic force microscope (AFM). The displacement in the depth direction before and after the diamond indenter is pushed in is measured with an optical displacement detector, and the change in load is measured. Further, an AFM image of the indentation of the thin film after removing the diamond indenter is obtained, and the indentation hardness is calculated using these pieces of information.

  As the reactive sputtering film forming conditions for forming the lower layer film, those found by conducting an experiment with a film forming apparatus that starts up in advance are used. In the experiment, for example, a thin film was formed on each substrate under various film formation conditions with a film forming apparatus that started up, the indentation hardness was measured for each thin film, and the film formation conditions and the thin film indentation were measured. The relationship of hardness is acquired, and the film forming conditions for the step of forming the lower layer film are selected.

  On the other hand, the upper film formed on the lower film is made of a material derived from a transition metal, silicon, and a reactive gas, and has an indentation hardness of less than 5000 MPa. The indentation hardness of the upper layer film is more preferably 4500 MPa or less, and further preferably 4000 MPa or less. This is because the lower the indentation hardness, the greater the effect obtained by the present invention. In the step of forming the upper layer film, after this film forming apparatus is started, reactive sputtering is performed under substantially the same film forming conditions as those for forming the pattern forming thin film on the substrate. In general, the aging process mainly brings the surface state of the target closer to the surface state of the target when the thin film for pattern formation is formed on the substrate by reactive sputtering after the film forming apparatus is started up. Done as a purpose. The surface state of the target after the step of forming the lower layer film is not close to the surface state of the target when the pattern forming thin film is formed on the substrate.

  By performing the process of forming the upper layer film, the thermal expansion and contraction of the shield is achieved with a laminated structure with the lower layer film while bringing the surface state of the target closer to the surface state of the target when the patterning thin film is formed on the substrate. It is possible to increase the resistance to the tensile force and the compressive force associated with. Since the lower layer film and the upper layer film are both formed of sputtered particles that are ejected from the target made of the same transition metal and silicon-containing material, both the lower layer film and the upper layer film are formed of the same transition metal and silicon-containing material. . From the viewpoint of the surface state of the target, the noble gas and reactive gas used in reactive sputtering when forming a lower layer film are the noble gas and reactive gas used in reactive sputtering when forming a thin film for pattern formation. The same is used. The ratio of the flow rate per unit time of the noble gas and reactive gas when forming the lower layer film by reactive sputtering is the unit of the noble gas and reactive gas when forming the thin film for pattern formation by reactive sputtering. The ratio of flow rate per hour is preferably the same. Film forming conditions such as a gas pressure in the film forming chamber and a voltage applied to the target are preferably the same when the lower layer film is formed by reactive sputtering and when the pattern forming thin film is formed.

  Used in reactive sputtering when forming the lower layer film from the viewpoint of reducing the difference in the surface state of the target when forming the lower layer film and the upper layer film and increasing the bonding force between the lower layer film and the upper layer film It is preferable that the at least one kind of reactive gas to be used is the same kind as the at least one kind of reactive gas used in the reactive sputtering when the upper layer film is formed. Furthermore, it is more preferable that all the reactive gases used in the reactive sputtering when forming the lower layer film are the same type as all the reactive gases used in the reactive sputtering when forming the upper layer film.

  The noble gas used when forming the upper layer film and the lower layer film is one or more gases selected from helium, neon, argon, krypton, and xenon. In particular, considering the sputtering efficiency from the target during reactive sputtering, the noble gas used when forming the upper layer film and the lower layer film contains one or more gases selected from argon, krypton, and xenon. It is preferable. When a thin film for pattern formation containing an element derived from a transition metal, silicon and a reactive gas is formed by reactive sputtering, the thin film tends to have a relatively high film stress. In order to reduce the film stress of the thin film, helium gas is preferably taken into the thin film during reactive sputtering. By annealing the substrate on which such a thin film is formed, the helium gas in the thin film is released into the atmosphere and a minute space is formed in the thin film. The stress of the thin film is reduced by moving other elements in the thin film into the minute space during annealing.

  Considering the viewpoint of sputtering efficiency when forming a thin film and the viewpoint of reducing the stress of the thin film, the noble gas used when forming the pattern forming thin film on the substrate is one or more selected from argon, krypton and xenon A mixed gas of the above gas and helium is preferable. In view of manufacturing cost, the noble gas is more preferably a mixed gas of argon and helium. The same applies to the lower layer film and the upper layer film that adhere to the inner wall surface of the shield in the aging process with respect to the film stress of the pattern forming thin film. Therefore, the noble gas used when forming the lower layer film and the upper layer film by reactive sputtering is also preferably a mixed gas of at least one gas selected from argon, krypton, and xenon and helium. Further, like the pattern forming thin film, the noble gas is more preferably a mixed gas of argon and helium.

  On the other hand, as will be described later, the noble gas flowing into the film forming chamber 2 is a mixed gas of argon gas and helium gas, the reactive gas is nitrogen gas, and the thin film is formed on the substrate by changing the film forming conditions. An experiment was carried out to perform reactive sputtering. Specifically, the flow rate of helium gas per unit time was changed without changing the flow rates of argon gas and nitrogen gas per unit time. And the indentation hardness of each formed thin film was measured. As a result, it was found that as the flow rate of helium per unit time increases, the indentation hardness of the thin film formed under the film forming conditions tends to increase.

  Considering the above results, the ratio of the flow rate per unit time of helium gas in the noble gas introduced into the film forming chamber 2 in the step of forming the lower layer film divided by the total flow rate per unit time of the noble gas is: It is preferable that the flow rate per unit time of the helium gas in the noble gas introduced into the film forming chamber 2 in the step of forming the upper layer film is larger than the ratio obtained by dividing the total flow rate per unit time of the noble gas. By doing in this way, it becomes possible to make the indentation hardness of a lower layer film into 5000 MPa or more and the indentation hardness of an upper layer film to less than 5000 MPa, making the element which comprises a lower layer film and an upper layer film the same.

A gas containing at least one of nitrogen, oxygen, carbon, and hydrogen can be used as the reactive gas used when forming the upper layer film and the lower layer film. On the other hand, a pattern forming thin film formed on a substrate using the film forming apparatus 1 often contains nitrogen as an element derived from a reactive gas. As the nitrogen content in the thin film increases, the extinction coefficient k tends to decrease while the refractive index n increases. A thin film having such optical characteristics is suitable for a halftone phase shift film. On the other hand, when manufacturing a transfer mask from a mask blank having a pattern forming thin film made of a transition metal silicide material, non-excited fluorine-based gas (XeF ₂ or the like) is supplied when correcting a black defect in the thin film pattern. On the other hand, correction is performed by irradiating an electron beam (EB defect correction). A thin film of a transition metal silicide-based material is easy to be etched even when it is exposed to XeF ₂ without being irradiated with an electron beam when the content of oxygen or nitrogen is small. Considering this point, even in the case of a light-shielding film made of a transition metal silicide material, nitrogen is used with a certain content or more.

From the above circumstances, in reactive sputtering when forming a pattern forming thin film of a transition metal silicide-based material, a gas containing nitrogen is often used as a reactive gas. For this reason, it can be said that the reactive gas in the step of forming the lower layer film and the step of forming the upper layer film, which are aging steps of the film forming apparatus 1, preferably includes at least a gas containing nitrogen. Examples of such reactive gas include N ₂ , NO, NO ₂ , NH ₃ , HNO _{3 and the} like.

  The target 9 is formed of a material containing a transition metal and silicon. A material in which an element derived from a reactive gas is contained in a transition metal and silicon is less malleable than a metal-based material and thus easily causes brittle fracture, and can be obtained by the method for starting the film forming apparatus of the first embodiment. This is because the effect is great. This is also because the transition metal silicide-based material thin film is suitable as a material for a light-shielding film or a halftone phase shift film. As the transition metal silicide material used in the thin film for pattern formation, molybdenum (Mo) has been widely used as a transition metal element so far, but is not limited thereto. As the transition metal element, tantalum (Ta), tungsten (W), titanium (Ti), chromium (Cr), hafnium (Hf), nickel (Ni), vanadium (V), zirconium (Zr), ruthenium (Ru) ), Rhodium (Rh), zinc (Zn), niobium (Nb), and palladium (Pd).

Ratio obtained by dividing the content [atomic%] of the transition metal (M) by the total content [atomic%] of the transition metal (M) and silicon (Si) in the thin film for pattern formation formed using the target 9 [ %] (Hereinafter, this ratio is referred to as “M / [M + Si] ratio”) is a numerical value close to the M / [M + Si] ratio of the target 9. The thin film of transition metal silicide-based material is a ratio in which the M / [M + Si] ratio is stoichiometrically stable (in the case of molybdenum silicide, it is MoSi ₂ , and many other transition metal silicides show the same tendency). In the range up to about 34% in the vicinity of.), The optical density with respect to ArF exposure light tends to increase as the M / [M + Si] ratio increases. On the other hand, the optical density tends to decrease as the M / [M + Si] ratio increases from about 34%.

  Further, the light resistance to ArF exposure light of the thin film of the transition metal silicide-based material decreases as the M / [M + Si] ratio increases. Considering these, the M / [M + Si] ratio in the target 9 is preferably less than 34%, more preferably 25% or less, and further preferably 20% or less. On the other hand, considering the conductivity of the target 9 and the conductivity of the pattern forming thin film, the M / [M + Si] ratio of the target 9 is preferably 1% or more, and more preferably 2% or more. .

  The method for starting up the film forming apparatus according to the first embodiment includes a mode in which the step of forming the lowermost layer film is performed before the step of forming the lower layer film on the inner wall surface of the shield. That is, the lower layer film of the present invention includes not only the case of being directly formed on the surface of the shield 7 but also the case of being formed on the surface of the shield 7 via the lowermost layer film. Specifically, in the step of forming the lowermost layer film, only the noble gas is introduced into the film forming chamber 2, and the transition metal and silicon are substantially formed on the surface of the shield 7 (on the inner wall surface of the shield) by sputtering. A lowermost layer film of the material to be formed is formed. The material consisting essentially of transition metal and silicon that forms the lowermost layer film is not only a material consisting only of transition metal and silicon, but also an element (noble gas) that is inevitable to be taken into the lowermost layer film during sputtering. In addition to the above, elements that cause contamination such as water) are included.

  When the shield 7 of the film forming apparatus 1 is replaced, the inside of the film forming chamber 2 is opened to the atmosphere. Since the target 9 is also open to the atmosphere, it is difficult to avoid the formation of an oxide film on the surface of the target 9. After replacement of the shield 7, an aging process for starting up the film forming apparatus 1 is performed. When a process of forming a lower layer film by reactive sputtering using a film forming gas containing a reactive gas is performed first, the target 9 Depending on the oxidation state of the surface, abnormal discharge may occur. When this abnormal discharge occurs, dust generation from the target 9 and deterioration of the surface state of the target 9 occur.

  In consideration of this point, it is preferable that sputtering is performed by introducing only a noble gas into the film forming chamber 2 and applying a voltage to the target 9 before performing the step of forming the lower layer film in the aging step. Only the noble gas particles collide with the surface of the target 9 and the constituent elements on the surface of the target 9 are blown off, whereby the surface layer including the oxide film of the target 9 can be removed. The transition metal and silicon particles jumping out of the target 9 adhere to the inner wall surface of the shield 7 to form the lowermost layer. Most of the oxygen ejected from the target 9 does not adhere to the shield 7 and is discharged out of the system from the gas discharge unit 6 together with the noble gas. For this reason, the lowermost layer film adhering to the inner wall surface of the shield 7 is formed of a material substantially composed of a transition metal and silicon.

  The lowermost layer film formed on the inner wall surface of the shield is a material that does not contain an element derived from a reactive gas. The lowermost layer film made of such a material has the same indentation hardness as that of the upper layer film, but has a significantly lower Young's modulus than the upper layer film and is easily elastically deformed. That is, the lowermost layer film is less susceptible to brittle fracture with respect to the thermal expansion and contraction of the shield 7 than the upper layer film. Further, since the lowermost layer film and the lower layer film are both materials containing the same transition metal and silicon, the chemical bond strength at the interface is relatively strong. By these actions, even if an adhesion film in which the lowermost layer film, the lower layer film, and the upper layer film are deposited in this order is formed on the inner wall surface of the shield 7, the adhesion film is prevented from generating dust and dropping due to the thermal expansion and contraction of the shield 7. Generation can be reduced.

  The step of forming the lowermost layer film is performed mainly for the purpose of bringing the surface of the target 9 close to the state of only the constituent elements of the target. Therefore, the noble gas introduced into the film forming chamber 2 has a relatively small atomic weight. It is preferable to use one of large argon, krypton, and xenon gas or a mixed gas of two or more gases selected from these gases.

  The first embodiment also provides a method for manufacturing a mask blank using the film forming apparatus that has been started up by the method for starting the film forming apparatus. Specifically, it is a method of manufacturing a mask blank having at least a pattern forming thin film on a substrate, and the substrate provided in the film forming apparatus 1 after being started up by the above-described method for starting up the film forming apparatus. A substrate 100 is set on the stage 3, a noble gas and a reactive gas are introduced, and a material containing a transition metal, silicon and a reactive gas-derived element is formed on the main surface of the substrate 100 by reactive sputtering. It has the process of forming the thin film for pattern formation whose indentation hardness derived | led-out by the tentation method is less than 5000 Mpa.

  The film formation conditions during the process of forming the pattern forming thin film on the substrate 100 are substantially the same as the film formation conditions during the process of forming the upper layer film on the inner wall surface of the shield 7. During the process of forming the pattern forming thin film, an adhesion film having substantially the same constituent elements and physical properties as the pattern forming thin film is newly formed on the upper layer film. However, since the newly formed adhesion film has substantially the same constituent elements and composition as the upper film, the bonding force between the upper film and the adhesion film is high. For this reason, the newly formed adhesion film is unlikely to fall off the upper layer film.

  The mask blank manufactured using this mask blank manufacturing method is made of a material containing an element derived from a transition metal, silicon and a reactive gas on the substrate 100, and has an indentation hardness derived by a nanoindentation method. Is provided with at least a thin film for pattern formation having a thickness of less than 5000 MPa. The pattern forming thin film is a thin film on which a transfer pattern is formed by etching when a transfer mask is manufactured from a mask blank. The thin film for pattern formation is used as a thin film having a transfer pattern in the final transfer mask, or temporarily as a hard mask film having a transfer pattern in the course of manufacturing a transfer mask from a mask blank. Also included are applications that exist in The thin film for pattern formation is used in applications such as a light shielding film, a phase shift film, a hard mask film, and an etching stopper film.

  When the transfer mask manufactured from the mask blank is a binary mask, the mask blank has a configuration in which a light shielding film is provided on the substrate 100 or a structure in which a hard mask film is laminated on the light shielding film. When the transfer mask manufactured from the mask blank is a halftone phase shift mask, the mask blank has a configuration in which a phase shift film and a light shielding film are provided on the substrate 100, or a hard mask film on the light shielding film. Is a laminated structure. In addition, a mask blank having an etching stopper film between the substrate 100 and the phase shift film and a mask blank having an etching stopper film between the phase shift film and the light shielding film are also included.

  ArF exposure light (wavelength 193 nm) using an ArF excimer laser as a light source is suitable as exposure light when a transfer mask manufactured from this mask blank is used in an exposure apparatus, but is not limited thereto. The present invention is also applicable to a mask blank for manufacturing a transfer mask used in an exposure apparatus to which KrF exposure light (wavelength 248 nm) and i-line exposure light (wavelength 365 nm) is applied.

  When the pattern forming thin film is a light shielding film for forming a light shielding pattern in a binary mask, the light shielding film is required to have an optical density (OD) of at least 2.0 with respect to exposure light. Is more preferably 5 or more, and further preferably 2.8 or more. When the pattern forming thin film is a light shielding film for forming a pattern including a light shielding band in a halftone phase shift mask, the light shielding film has a laminated structure with a phase shift film and has an optical density (OD) with respect to exposure light. Is required to be at least 2.0, more preferably 2.5 or more, and even more preferably 2.8 or more.

  When the thin film for pattern formation is a phase shift film for forming a phase shift pattern in a halftone type phase shift mask, this phase shift film has a transmittance of 1% to 30% for exposure light. The phase difference generated between ArF exposure light transmitted through the phase shift film and light that has passed through the air by the same distance as the thickness of the phase shift film is in the range of 150 to 190 degrees. It is preferable to be adjusted to.

  The pattern forming thin film may have either a single layer structure or a laminated structure of two or more layers. In addition, each layer of the pattern forming thin film having a single layer structure and the pattern forming thin film having a laminated structure of two or more layers has the same composition in the thickness direction of the film or the layer, but the layer thickness direction The composition may be inclined at the composition. However, regardless of the configuration of the thin film for pattern formation, the thin film initially formed by reactive sputtering on the substrate 100 in the film forming apparatus 1 after the start-up by the method of the first embodiment is indented. The hardness is required to be less than 5000 MPa. It is more preferable that the first thin film is formed under substantially the same film formation conditions as when the upper layer film of the shield 7 was formed (that is, the first thin film has substantially the same composition as the upper layer film). .) This is because the thin film formed first is a film that first adheres to the upper layer film of the shield 7.

The substrate 100 is preferably a translucent substrate having translucency for exposure light. The substrate 100 is preferably formed of a glass material. The substrate 100 can be formed of synthetic quartz glass, quartz glass, aluminosilicate glass, soda lime glass, low thermal expansion glass (SiO ₂ —TiO ₂ glass or the like), and the like. Among these, synthetic quartz glass is particularly preferable as a material for forming a mask blank substrate because it has a high transmittance with respect to ArF exposure light and has a sufficient rigidity that hardly causes deformation.

  The positional relationship between the substrate 100 and the target 9 when forming the pattern forming thin film will be described with reference to FIG. The offset distance Doff (the distance between the center axis 21 of the substrate 100 and the straight line 22 passing through the center of the target 9 and parallel to the center axis 21 of the substrate 100) is the in-plane uniformity of the film thickness of the pattern forming thin film. Can be adjusted according to the area to be secured. In general, when the area where good in-plane uniformity is to be ensured is large, the necessary offset distance Doff increases. For example, in the case of a quadrangular substrate 100 with a side of 152 mm, the region where the transfer pattern is formed on the thin film is usually a rectangular inner region with a side of 132 mm with respect to the center of the substrate 100. In order to realize the accuracy within ± 1 nm of the film thickness distribution of the thin film on the inner side of the square having a side of 132 mm, the offset distance Doff needs to be about 240 mm to 400 mm, and the preferable offset distance Doff is from 300 mm. 380 mm.

  The optimum range of the vertical distance (H) between the target 9 and the substrate 100 varies depending on the offset distance Doff. For example, in order to ensure good in-plane uniformity within a rectangular substrate 100 having a side of 152 mm, the vertical distance (H) between the target 9 and the substrate 100 needs to be about 200 mm to 380 mm, and preferable H is 210 mm to 300 mm. The target inclination angle θ affects not only the in-plane uniformity of the thin film thickness but also the film formation rate. Specifically, the target inclination angle θ is preferably 10 degrees to 30 degrees in order to obtain a good in-plane uniformity of the film thickness of the thin film and a large film formation rate.

[Second Embodiment]
On the other hand, according to the present invention, in the aging process of the film forming apparatus 1, after performing the process of forming the lower layer film on the inner wall surface of the shield 7, the film forming apparatus 1 does not perform the process of forming the upper layer film. A second embodiment in which a mask blank is manufactured by forming a pattern forming thin film on the substrate 100 is included. That is, the mask blank manufacturing method according to the second embodiment uses a film forming apparatus 1 including a target 9 made of a material containing a transition metal and silicon, a shield 7 and a substrate stage 3 in the film forming chamber 2. A method for manufacturing a mask blank, which comprises at least a pattern forming thin film on a substrate 100, introduces a noble gas and a reactive gas into the film forming chamber 2, and is formed on the surface of the shield 7 by reactive sputtering. Forming a lower layer film having an indentation hardness of 5000 MPa or more derived from a material containing an element derived from a transition metal, silicon and a reactive gas, and a substrate stage in the film forming chamber 2 The substrate 100 is placed on the substrate 3, noble gas and reactive gas are introduced, and the main substrate 100 is formed by reactive sputtering. Forming a thin film for pattern formation, which is made of a material containing an element derived from a transition metal, silicon and a reactive gas on the surface and has an indentation hardness of less than 5000 MPa derived by a nanoindentation method. It is characterized by.

  In this second embodiment, even if the surface state of the target 9 after performing the step of forming the lower layer film is the surface state as it is and the pattern forming thin film is formed by reactive sputtering, the surface of the target 9 is abnormal. This is particularly effective when dust generation such as electric discharge is unlikely to occur and the film thickness distribution and optical characteristics of the pattern forming thin film formed on the substrate 100 can be made highly uniform. In the mask blank manufacturing method of this embodiment, on the lower layer film in which the deposited film made of the same material as the material forming the pattern forming thin film is formed on the surface of the shield 7 during the step of forming the pattern forming thin film. Also formed. Since this deposited film is the same constituent element as the lower layer film, the chemical bonding force between the lower layer film and the lower layer film is high.

  Also in the case of the second embodiment, matters relating to the noble gas are the same as in the case of the relationship between the lower layer film and the upper layer film in the first embodiment. Also in the case of the second embodiment, the noble gas used when forming the lower layer film and the pattern forming thin film is preferably a mixed gas of one or more gases selected from argon, krypton and xenon and helium. . Further, the ratio obtained by dividing the flow rate per unit time of the helium gas in the noble gas introduced into the film forming chamber in the step of forming the lower layer film by the total flow rate per unit time of the noble gas forms the pattern forming thin film. The ratio is preferably larger than the ratio obtained by dividing the flow rate per unit time of helium gas in the noble gas introduced into the film forming chamber in the process by the total flow rate per unit time of the noble gas.

  Also in the case of the second embodiment, matters relating to the reactive gas are the same as in the case of the relationship between the lower layer film and the upper layer film in the first embodiment. Also in the case of the second embodiment, the reactive gas in the step of forming the lower layer film and the step of forming the pattern forming thin film preferably includes at least a gas containing nitrogen. Also in the case of the second embodiment, the matters relating to the target 9 are the same as in the case of the first embodiment. The M / [M + Si] ratio in the target is preferably less than 34%. Other matters are the same as those in the first embodiment, except that the step of forming the upper layer film on the lower layer film formed on the inner wall surface of the shield 7 is not performed in the second embodiment.

  The present invention includes a step of forming a transfer pattern on a thin film for pattern formation by dry etching using the mask blank manufactured by the mask blank manufacturing method of either the first embodiment or the second embodiment. A featured transfer mask manufacturing method is included.

  When the transfer mask is a binary mask, for example, the binary mask is manufactured by the following manufacturing method. First, by using the mask blank manufacturing method of the first embodiment or the second embodiment, a mask blank in which a light shielding film (pattern forming thin film) and a hard mask film are stacked on the substrate 100 is manufactured. The hard mask film is preferably formed of a material containing chromium. Next, a resist film for electron beam lithography exposure is formed on the hard mask film by a spin coating method. Subsequently, after a transfer pattern is drawn and exposed on the resist film by an electron beam drawing apparatus, a developing process or the like is performed to form a resist pattern.

  Next, using the resist pattern as a mask, dry etching is performed with a mixed gas of chlorine-based gas and oxygen gas to form a transfer pattern on the hard mask film. Next, using the hard mask film having the transfer pattern as a mask, dry etching using a fluorine-based gas is performed to form a transfer pattern on the light shielding film. Finally, the hard mask film is removed by dry etching or the like, and a predetermined process such as a cleaning process is performed to complete a binary mask. In the manufacture of the binary mask, a hard mask film may not be provided on the mask blank, and the resist film may be directly formed on the light shielding film after performing a HMDS (hexamethyldisilazane) process on the surface of the light shielding film.

  When the transfer mask is a halftone phase shift mask, for example, the halftone phase shift mask is manufactured by the following manufacturing method. First, by using the mask blank manufacturing method of the first embodiment or the second embodiment, a mask blank in which a phase shift film (pattern forming thin film) and a light shielding film are stacked on the substrate 100 is manufactured. The light shielding film is preferably formed of a material containing chromium. Next, an electron beam drawing exposure resist film is formed on the light shielding film by a spin coating method. Subsequently, after a transfer pattern is drawn and exposed on the resist film by an electron beam drawing apparatus, a development process or the like is performed to form a first resist pattern.

  Next, using the first resist pattern as a mask, dry etching is performed with a mixed gas of chlorine gas and oxygen gas to form a transfer pattern on the light shielding film. Next, using the light-shielding film having the transfer pattern as a mask, dry etching with a fluorine-based gas is performed to form a transfer pattern on the phase shift film. Next, a resist film is newly formed on the light shielding film, a pattern including a light shielding band is drawn and exposed on the resist film, and development processing or the like is performed to form a second resist pattern. Next, using the second resist pattern as a mask, dry etching with a mixed gas of chlorine-based gas and oxygen gas is performed to form a pattern including a light shielding band on the light shielding film. Finally, a predetermined process such as a cleaning process is performed to complete a halftone phase shift mask.

  In the manufacture of the above halftone phase shift mask, a hard mask film made of a material containing silicon is provided on the light shielding film of the mask blank, the surface of the hard mask film is subjected to HMDS treatment, and then the resist film is formed. It may be formed on the hard mask film.

  The present invention provides a method for manufacturing a semiconductor device, comprising a step of exposing and transferring a transfer pattern onto a resist film on a semiconductor substrate using the transfer mask manufactured by the above-described transfer mask manufacturing method. included.

Hereinafter, embodiments of the present invention will be described more specifically with reference to examples.
(Examples and Comparative Examples)
[Start-up of deposition system]
In this embodiment, a mask blank for a halftone phase shift mask to which ArF exposure light is applied is manufactured. The mask blank has a structure in which a phase shift film, a light shielding film, and a hard mask film are laminated in this order on a synthetic quartz glass substrate 100 (the main surface has a dimension of about 152 mm × about 152 mm and a thickness of about 6.35 mm). Prepare. Among them, the phase shift film is a pattern forming thin film made of a transition metal, silicon and nitrogen. This phase shift film has optical characteristics with a transmittance of 6% for ArF exposure light and a phase difference of 177 degrees.

This phase shift film is formed on the substrate 100 using the DC magnetron sputtering film forming apparatus 1. Specifically, using a mixed target 9 (Mo: Si = 4: 96 atomic% ratio) of molybdenum (Mo) and silicon (Si), nitrogen (N ₂ ), argon (Ar) and A mixed gas of helium (He) (flow rate ratio [sccm] N ₂ : Ar: He = 18: 9: 30, pressure = 0.3 Pa) is introduced from the gas inflow portion 5, and 2. to the cathode 4 (target 9). A voltage was applied at a power of 4 kW, and a phase shift film having a thickness of 61 nm was formed by reactive sputtering. When the indentation hardness of the formed phase shift film was measured by the nanoindentation method using an additional function of an atomic force microscope (Dimension Icon manufactured by Bruker), it was 3145 [MPa]. . Since the indentation hardness of this phase shift film is less than 5000 [MPa], in the conventional method of starting the film forming apparatus, dust generation and film peeling from the deposited film adhering to the inner wall surface of the shield 7 frequently occur. End up. When the film forming apparatus used for forming the phase shift film is started up by the method for starting the film forming apparatus of the present invention, defects in the phase shift film are reduced.

  In order to use the start-up method of the film forming apparatus of the present invention, the film forming conditions used in the step of forming the lower layer film on the inner wall surface of the shield 7, that is, the lower layer film of 5000 MPa or more on the inner wall surface of the shield 7 is used. It is necessary to select the film forming conditions to be formed. Therefore, an experiment was performed by changing the conditions with reference to the film forming conditions when forming the phase shift film with the film forming apparatus 1, and the film forming conditions for forming the lower layer film were selected. Since the same target 9 is used when forming the lower layer film and when forming the phase shift film, the mixing ratio of molybdenum and silicon cannot be changed. Therefore, first, the flow rates per unit time of argon gas and helium gas flowing into the film forming chamber 2 are constant (Ar = 9 [sccm], He = 30 [sccm]), and the flow rate of nitrogen gas per unit time. The thin film was formed on each substrate by varying the above, and the indentation hardness and Young's modulus of each thin film were measured in the same manner as described above (the above-mentioned atomic force microscope can also measure Young's modulus with an additional function). .

  FIG. 2 is a graph showing the relationship between the flow rate [sccm] of nitrogen gas per unit time during reactive sputtering for forming a thin film and the indentation hardness [MPa] of the formed thin film. FIG. 3 is a graph showing the relationship between the flow rate [sccm] of nitrogen gas per unit time during reactive sputtering for forming a thin film and the Young's modulus [MPa] of the formed thin film. From the graph of FIG. 2, it can be seen that even if the flow rate of nitrogen gas per unit time is changed, the indentation hardness of the thin film does not fluctuate greatly, and there is no film forming condition of 5000 [MPa] or more. It can be seen from the graph of FIG. 3 that the Young's modulus of the thin film tends to increase as the flow rate of nitrogen gas per unit time increases. Since the flow rate of nitrogen gas per unit time has a correlation with the nitrogen content of the thin film, a thin film made of a material containing silicon, molybdenum (transition metal) and nitrogen has a higher Young's modulus as the nitrogen content increases. It can also be seen that there is a tendency to become.

  In FIG. 2, when the flow rate of nitrogen gas per unit time is zero (that is, when sputtering is performed only with argon gas and helium gas), the Young's modulus of the thin film is the lowest. Since this thin film has a low Young's modulus, it is relatively difficult to cause brittle fracture when an external force is applied. The film formation conditions are substantially the same as the film formation conditions for sputtering in which only the noble gas is introduced at the initial stage of starting up the conventional film formation apparatus to clean the surface of the target. From this result, even if the lowermost layer film of molybdenum silicide (transition metal silicide) is first attached to the inner wall surface of the shield 7 by sputtering for cleaning the surface of the target, the tensile force applied to the lowermost layer film by the thermal expansion and contraction of the shield 7 In addition, it can be said that it is difficult to cause brittle fracture or dropout due to compressive force.

Next, the flow rate per unit time of nitrogen gas and argon gas flowing into the film formation chamber 2 is constant (N ₂ = 18 [sccm], Ar = 9 [sccm]), and the flow rate of helium gas per unit time The thin film was formed on each substrate by varying the above, and the indentation hardness and Young's modulus of each thin film were measured in the same manner as described above (the above-mentioned atomic force microscope can also measure Young's modulus with an additional function). . FIG. 4 is a graph showing the relationship between the flow rate [sccm] of helium gas per unit time during reactive sputtering for forming a thin film and the indentation hardness [MPa] of the formed thin film. FIG. 5 is a graph showing the relationship between the flow rate [sccm] of helium gas per unit time during reactive sputtering for forming a thin film and the Young's modulus [MPa] of the formed thin film.

  It can be seen from the graph of FIG. 4 that the indentation hardness of the thin film tends to increase as the flow rate of helium gas per unit time increases. Further, the graph of FIG. 5 shows that the Young's modulus of the thin film tends to increase as the flow rate of helium gas per unit time increases. From the result of FIG. 4, in the case of this film forming apparatus 1, if the flow rate per unit time of helium is changed to 45 [sccm] or more from the film forming conditions of the above-described phase shift film, the deposition attached to the inner wall surface of the shield 7 The indentation hardness of the film can be 5000 [MPa] or more.

  At first glance, it seems that it is only necessary to change the deposition condition of the phase shift film so that the flow rate of helium per unit time is 45 [sccm] or more. However, increasing the flow rate per unit time of helium in the film formation conditions of the phase shift film slightly reduces the amount of nitrogen taken into the phase shift film when the phase shift film is formed by reactive sputtering, The amount of helium taken into the phase shift film increases. Even if the change in the composition of the phase shift film is not large, the optical characteristics change relatively greatly. For this reason, the film forming conditions themselves of the phase shift film cannot be changed.

  Based on the above results, the film forming apparatus 1 of the example of the present invention was started up. Specifically, first, a mixed target 9 (Mo: Si = 4: 96 atomic% ratio) of molybdenum (Mo) and silicon (Si) bonded to the backing plate 8 via an indium bonding material was prepared. . A lower shield 71 and an upper shield 72 are attached in the film formation chamber 2 of the DC magnetron sputtering film formation apparatus 1, and the target 9 is attached to the cathode 4. After evacuating the film forming chamber 2, a dummy substrate was placed on the substrate stage 3. Next, only argon gas is introduced into the film forming chamber 2 from the gas inflow portion 5 at a flow rate of 15 [sccm], and a voltage is applied to the cathode 4 (target 9) with a power of 0.4 [kW], and argon gas is applied. Only plasma was generated in the film forming chamber 2. And the argon particle was made to collide with the target 9, and the surface of the target 9 was cleaned weakly (process for forming a lowermost layer film). Subsequently, the power to the cathode 4 was increased to 1.4 [kW] to clean the surface of the target 9 (step of forming the lowermost layer film).

  By performing the weak cleaning and the strong cleaning, contaminants such as organic substances adhering to the surface of the target 9 and the surface oxide film have been removed. Further, during the weak cleaning and the strong cleaning, molybdenum and silicon particles were ejected from the surface of the target 9 and were deposited as the lowermost layer film on the inner wall surface of the shield 7. This lowermost layer film has an indentation hardness of less than 5000 [MPa] but a Young's modulus of less than 10,000 [MPa], so that the shield 7 has high resistance to thermal expansion and contraction.

Next, the power supply to the cathode 4 is stopped, and the flow rate of the mixed gas of nitrogen (N ₂ ), argon (Ar) and helium (He) from the gas inflow portion 5 into the film formation chamber 2 (flow rate ratio [sccm] N ₂ : Ar: He = 18: 9: 50, pressure = 0.3 Pa). When the flow rate ratio of the mixed gas in the film forming chamber 2 is stabilized, a voltage is applied to the cathode 4 (target 9) with a power of 2.4 [kW] to cause reactive sputtering, which is formed on the inner wall surface of the shield 7 A lower layer film (MoSiN film) made of a material containing molybdenum, silicon and nitrogen was formed on the lowermost layer film (step of forming the lower layer film). It can be said that the indentation hardness is about 5500 [MPa] from the result of FIG.

  In the step of forming the lower layer film, the dummy substrate is replaced every time the MoSiN film is formed with a thickness of 60 nm on one dummy substrate. Here, 30 dummy substrates are used. Therefore, it can be said that the average thickness of the lower layer film (MoSiN film) formed on the lowermost layer film formed on the inner wall surface of the shield 7 is about 1.8 μm.

Next, the power supply to the cathode 4 is stopped, and the flow rate ratio of the mixed gas introduced from the gas inflow portion 5 into the film formation chamber 2 is changed to the flow rate ratio (flow rate ratio [sccm] N ₂ : Ar: He = 18: 9: 30) and pressure (pressure = 0.3 Pa). When the flow rate ratio of the mixed gas in the film forming chamber 2 is stabilized, a voltage is applied to the cathode 4 (target 9) with a power of 2.4 [kW] to cause reactive sputtering, which is formed on the inner wall surface of the shield 7 An upper layer film (MoSiN film) made of a material containing molybdenum, silicon and nitrogen was formed on the formed lower layer film (step of forming an upper layer film). The upper layer film has an indentation hardness of approximately 3145 [MPa] from the result of FIG. 4 and is less than 5000 [MPa]. As a result of performing this step, the surface state of the target 9 is substantially the same as that when performing reactive sputtering for forming the phase shift film.

  Also in the step of forming the upper layer film, the dummy substrate is replaced every time the MoSiN film is formed with a thickness of 60 nm on one dummy substrate, and 30 dummy substrates are also used here. Therefore, it can be said that the average thickness of the upper layer film (MoSiN film) formed on the lower layer film formed on the inner wall surface of the shield 7 is about 1.8 μm.

Using the film forming apparatus 1 started up in the above procedure, a step of forming a phase shift film on the substrate 100 made of synthetic quartz glass by reactive sputtering was performed. Specifically, the substrate 100 is placed on the substrate stage, and the flow rate of the mixed gas of nitrogen (N ₂ ), argon (Ar), and helium (He) from the gas inflow portion 5 into the film formation chamber 2 (flow rate ratio [sccm N ₂ : Ar: He = 18: 9: 30, pressure = 0.3 Pa) was introduced. When the flow ratio of the mixed gas in the film forming chamber 2 is stabilized, a voltage is applied to the cathode 4 (target 9) with a power of 2.4 [kW] to cause reactive sputtering, and the substrate 100 is made of MoSiN. A phase shift film was formed with a thickness of 61 nm.

  The step of forming the phase shift film was performed on 100 substrates 100. Next, 100 substrates 100 on which the phase shift film was formed were subjected to a phase shift film defect inspection using a mask blank defect inspection apparatus (M6640 manufactured by Lasertec Corporation). A screening process was performed using a phase shift film in which defects equivalent to 100 nm were not detected in the defect inspection as acceptance criteria. As a result, 51 out of 100 sheets could be selected as satisfying the acceptance criteria. The ratio (yield) of this acceptable product was greatly improved as compared with the case where the phase shift film was formed on the substrate by the film forming apparatus started up by the conventional start-up method.

  On the other hand, as a comparative example, a phase shift film was formed on a substrate with a film forming apparatus which was started up by a conventional start-up method. In the start-up method of this comparative example, the same process as the above-described example was performed for the process of forming the lowermost layer film on the inner wall surface of the shield 7. The difference from the start-up method of Example 1 was that the step of forming the upper layer film was performed without performing the step of forming the lower layer film on the lowermost layer film deposited on the inner wall surface of the shield 7. However, the process of forming the upper layer film of the comparative example was performed for 60 dummy substrates. Therefore, in this comparative example, it can be said that the average thickness of the upper layer film (MoSiN film) formed on the lowermost layer film formed on the inner wall surface of the shield 7 is about 3.6 μm.

Using the film forming apparatus 1 started up by the start-up method of the above comparative example, a step of forming a phase shift film by reactive sputtering on the substrate 100 made of synthetic quartz glass is performed as in the case of the example. It was. Furthermore, the defect inspection of the phase shift film was performed on the 100 substrates 100 on which the phase shift film of the comparative example was formed with a mask blank defect inspection apparatus (M6640 manufactured by Lasertec Corporation). A screening process was performed using a phase shift film in which defects equivalent to 100 nm were not detected in the defect inspection as acceptance criteria. As a result, 29 out of 100 sheets were selected as satisfying the acceptance criteria. The ratio of acceptable products (yield) can be said to be quite low.
[Manufacture of mask blanks]

Next, the substrate 100 provided with the phase shift film selected as an acceptable product in the screening process of the above example was placed in a film forming chamber of another DC magnetron sputtering film forming apparatus. Using a chromium (Cr) target, reactive sputtering is performed using a mixed gas of argon (Ar), carbon dioxide (CO ₂ ), nitrogen (N ₂ ), and helium (He) as a sputtering gas, and then on the phase shift film. A light-shielding film made of CrOCN (Cr: O: C: N = 55 atomic%: 22 atomic%: 12 atomic%: 11 atomic%) was formed to a thickness of 46 nm. The composition of the light shielding film is analyzed by X-ray photoelectron spectroscopy (XPS: X-ray Photoelectron Spectroscopy, RBS: with Rutherford Backscattering Spectrometry correction). The optical density (OD) at a wavelength of 193 nm in the laminated structure of the phase shift film and the light shielding film was measured and found to be 3.0 or more.

Next, the substrate 100 on which the phase shift film and the light-shielding film are stacked is placed in an RF magnetron sputtering film forming apparatus, a silicon dioxide (SiO ₂ ) target is used, and argon (Ar) gas is used as a sputtering gas. RF sputtering was performed to form a hard mask film made of silicon and oxygen with a thickness of 5 nm on the light shielding film. By the above method, the mask blank of the Example which has the structure where the phase shift film, the light shielding film, and the hard mask film were laminated | stacked on the board | substrate 100 was manufactured.

[Manufacture of phase shift mask]
Next, using the mask blank manufactured by the film forming apparatus after being started up by the method of starting the film forming apparatus of this example, the phase shift mask of the example was manufactured in the following procedure. First, the surface of the hard mask film was subjected to HMDS treatment. Subsequently, a resist film made of a chemically amplified resist for electron beam drawing was formed with a film thickness of 100 nm in contact with the surface of the hard mask film by spin coating. Next, a first pattern, which is a phase shift pattern to be formed on the phase shift film, is drawn on the resist film by electron beam, a predetermined development process is performed, and a first resist pattern having the first pattern is formed. Formed.

Next, using the first resist pattern as a mask, dry etching using CF ₄ gas was performed to form the first pattern on the hard mask film. Next, the first resist pattern was removed by ashing or stripping solution. Subsequently, using the hard mask film having the first pattern as a mask, dry etching using a mixed gas of chlorine and oxygen (gas flow ratio Cl ₂ : O ₂ = 4: 1) is performed, and the first light shielding film is formed on the light shielding film. A pattern (first light shielding pattern) was formed. Next, using the light-shielding film having the first pattern as a mask, dry etching using a fluorine-based gas (SF ₆ + He) is performed to form the first pattern (phase shift pattern) on the phase shift film, and at the same time The hard mask film was removed.

Next, a resist film made of a chemically amplified resist for electron beam drawing was formed with a film thickness of 150 nm on the light shielding film by spin coating. Next, a second pattern, which is a pattern (light-shielding pattern) to be formed on the light-shielding film, is exposed and drawn on the resist film, and further subjected to a predetermined process such as a development process, whereby the second resist having the light-shielding pattern A pattern was formed. Subsequently, dry etching using a mixed gas of chlorine and oxygen (gas flow ratio Cl ₂ : O ₂ = 4: 1) is performed using the second resist pattern as a mask, and the second pattern (light shielding pattern) is formed on the light shielding film. ) Was formed. Further, the second resist pattern was removed, and a predetermined process such as cleaning was performed to obtain the phase shift mask of the example.

  When the mask pattern was inspected by the mask inspection apparatus with respect to the halftone phase shift mask of the manufactured example, no defect due to the phase shift film was detected. It was confirmed that a highly accurate phase shift mask was produced.

  For the halftone phase shift mask of this example, a transfer image was simulated when AIMS 193 (manufactured by Carl Zeiss) was exposed and transferred to a resist film on a semiconductor device with exposure light having a wavelength of 193 nm. When the exposure transfer image of this simulation was verified, the design specifications were sufficiently satisfied. From this result, even if the phase shift mask of the example is set on the mask stage of the exposure apparatus and exposed and transferred to the resist film on the semiconductor device, the circuit pattern finally formed on the semiconductor device is formed with high accuracy. I can say that.

DESCRIPTION OF SYMBOLS 1 Film-forming apparatus 2 Film-forming chamber 3 Substrate stage 31 Rotating shaft 4 Cathode 5 Gas inflow part 6 Gas exhaust part 7 Shield 71 Lower shield 72 Upper shield 8 Backing plate 9 Target 21 Central axis 22 Straight line

Claims (14)

A method of starting a film forming apparatus provided with a target and a shield made of a material containing a transition metal and silicon in a film forming chamber,
Introducing a noble gas and a reactive gas into the film forming chamber, and comprising a material containing the transition metal, silicon and the element derived from the reactive gas on the surface of the shield by reactive sputtering, and by a nanoindentation method Forming a lower layer film having an indentation hardness of 5000 MPa or more,
A noble gas and a reactive gas are introduced into the film forming chamber, and a nanoindentation made of a material containing the transition metal, silicon and the element derived from the reactive gas on the lower layer film of the shield by reactive sputtering. And a step of forming an upper film whose indentation hardness is less than 5000 MPa, which is derived by the method.   2. The method for starting up a film forming apparatus according to claim 1, wherein the noble gas is a mixed gas of at least one gas selected from argon, krypton and xenon and helium.   The ratio obtained by dividing the flow rate per unit time of helium gas in the noble gas introduced into the film forming chamber in the step of forming the lower layer film by the total flow rate per unit time of the noble gas forms the upper layer film. 3. The ratio of the flow rate per unit time of the helium gas in the noble gas introduced into the film forming chamber in the step of dividing by the total flow rate per unit time of the noble gas is larger. Method of starting the film forming apparatus.   The film forming apparatus according to claim 1, wherein the reactive gas in the step of forming the lower layer film and the step of forming the upper layer film includes at least a gas containing nitrogen. Startup method.   5. The film forming apparatus according to claim 1, wherein a ratio obtained by dividing the content of the transition metal by the total content of the transition metal and silicon in the target is less than 34%. Startup method. A mask blank manufacturing method using a film forming apparatus after being started up by the method for starting a film forming apparatus according to claim 1,
The mask blank comprises at least a pattern forming thin film on a substrate,
The substrate is set on a substrate stage provided in the film forming apparatus after the start-up, a noble gas and a reactive gas are introduced into the film forming chamber, and the main surface of the substrate is formed by reactive sputtering. Comprising a step of forming a thin film for pattern formation comprising a material containing an element derived from the transition metal, silicon and the reactive gas and having an indentation hardness of less than 5000 MPa derived by a nanoindentation method. A method for manufacturing a mask blank. In the film forming chamber, a mask blank manufacturing method using a film forming apparatus including a target made of a material containing a transition metal and silicon, a shield, and a substrate stage,
The mask blank comprises at least a pattern forming thin film on a substrate,
Introducing a noble gas and a reactive gas into the film forming chamber, and comprising a material containing the transition metal, silicon and the element derived from the reactive gas on the surface of the shield by reactive sputtering, and by a nanoindentation method Forming a lower layer film having an indentation hardness of 5000 MPa or more,
The substrate is placed on a substrate stage in the film forming chamber, a noble gas and a reactive gas are introduced into the film forming chamber, and the transition metal, silicon, and the reaction are formed on the main surface of the substrate by reactive sputtering. And a step of forming a pattern-forming thin film having an indentation hardness of less than 5000 MPa, which is made of a material containing an element derived from a property gas and derived by a nanoindentation method.   8. The mask according to claim 7, wherein in the step of forming the pattern forming thin film, a deposited film made of the same material as that constituting the pattern forming thin film is also formed on the lower layer film of the shield. Blank manufacturing method.   9. The method of manufacturing a mask blank according to claim 7, wherein the noble gas is a mixed gas of at least one gas selected from argon, krypton, and xenon and helium.   The ratio obtained by dividing the flow rate per unit time of the helium gas in the noble gas introduced into the film forming chamber in the step of forming the lower layer film by the total flow rate per unit time of the noble gas is the thin film for pattern formation The ratio of the flow rate per unit time of the helium gas in the noble gas introduced into the film forming chamber in the step of forming the gas is larger than the ratio obtained by dividing the total flow rate per unit time of the noble gas. 9. A method for producing a mask blank according to 9.   The mask blank according to claim 7, wherein the reactive gas in the step of forming the lower layer film and the step of forming the pattern forming thin film includes at least a gas containing nitrogen. Manufacturing method.   The ratio of the content of the transition metal divided by the total content of the transition metal and silicon in the target is less than 34%, The mask blank production according to any one of claims 7 to 11, Method.   A transfer mask comprising a step of forming a transfer pattern on the thin film for pattern formation by dry etching using the mask blank manufactured by the method for manufacturing a mask blank according to claim 6. Manufacturing method.   A method for manufacturing a semiconductor device, comprising: a step of exposing and transferring a transfer pattern onto a resist film on a semiconductor substrate using the transfer mask manufactured by the method for manufacturing a transfer mask according to claim 13.

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