JP2017044892A - Mask blank manufacturing method, transfer mask manufacturing method, and mask blank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a mask blank in which a hard mask film constituted by using a silicon-based compound can be patterned with high accuracy even immediately after a resist pattern is formed.SOLUTION: The method for manufacturing a mask blank includes: a film formation step of successively forming a pattering material film and a silicon-containing hard mask film in this order on a substrate; a modification step of modifying a silanol group on a surface of the hard mask film with a chemical modification group by a treatment using an organic silicon compound; and a step of forming a resist film on the modified hard mask film. The modification treatment is carried out to obtain a contact angle of 40° or more and 55° or less with water on the surface of the hard mask film at room temperature of 23°C.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a mask blank manufacturing method, a transfer mask manufacturing method, and a mask blank.

  Some thin films provided on a substrate in a mask blank have a hard mask film made of a silicon compound on the outermost surface. Since a thin film made of a silicon compound is excellent in dry etching resistance to a chlorine-based gas, it is useful as a mask pattern when a chromium-based thin film used as a light-shielding film is dry-etched with a chlorine-based gas. Further, even if an extremely thin film having a thickness of 5 nm or less functions as a mask, the resist film used as a mask when the hard mask film is etched can be thinned. This makes it possible to transfer a fine pattern having a dimension of 100 nm or less to the thin film on the substrate.

  Here, the surface of the hard mask film made of a silicon-based compound is a polar surface, and adhesion to a resist film made of an organic compound having low polarity is not sufficient. For this reason, for example, in the formation of a fine pattern with a line width of 50 nm or less, pattern collapse of the resist pattern formed on the resist film by lithography occurs. Therefore, in the mask blank manufacturing process, before the resist film is formed on the upper part of the thin film, a surface modification process for improving adhesion is performed on the surface of the hard mask film. In this surface modification treatment, for example, HMDS (hexamethyldisilazane) evaporated using, for example, nitrogen gas is brought into contact with the hard mask film to form a very thin hydrophobic surface layer on the surface of the hard mask film. (For example, refer to Patent Document 1 below).

JP 2014-59575 A

  By the way, in manufacturing a transfer mask using a mask blank, it is preferable to immediately etch the underlying hard mask film using the resist pattern as a mask after the resist pattern is formed by lithography processing of the resist film. This is because deterioration of the etching shape of the lower layer due to foreign matters adhering to the resist pattern is prevented.

  However, even when the underlying hard mask film is etched immediately after the resist pattern is formed, a phenomenon occurs in which defects occur in the hard mask pattern.

  Therefore, the present invention provides a mask blank manufacturing method capable of patterning a hard mask film composed of a silicon-based compound with high accuracy even immediately after formation of a resist pattern, and good shape accuracy. An object of the present invention is to provide a method for manufacturing a transfer mask having a fine pattern.

<Configuration 1>
A film forming process for forming a patterning material film and a silicon-containing hard mask film on the substrate in this order;
A modification treatment step of modifying a silanol group on the surface of the hard mask film with a chemical modification group by treatment with an organosilicon compound;
Forming a resist film on the modified hard mask film,
The said modification process is performed so that the water contact angle of the surface of the said hard mask film | membrane in room temperature 23 degreeC may be in the range of 40 degrees or more and 55 degrees or less.

<Configuration 2>
A film forming process for forming a patterning material film and a silicon-containing hard mask film on the substrate in this order;
A modification treatment step of modifying a silanol group on the surface of the hard mask film with a chemical modification group by treatment with an organosilicon compound;
Forming a resist film on the modified hard mask film,
The said modification process is a mask blank manufacturing method which performs a process so that the coverage by the said chemical modification group of the said silanol group may be in the range of 45% or more and 85% or less when a saturation coverage is 100%.

<Configuration 3>
In the film forming step, a material film containing chromium is formed as the patterning material film. A method of manufacturing a mask blank according to Configuration 1 or 2, wherein:

<Configuration 4>
The said organosilicon compound has an amine. The manufacturing method of the mask blank in any one of the structures 1-3 characterized by the above-mentioned.

<Configuration 5>
The said organosilicon compound is hexamethyldisilazane. The manufacturing method of the mask blank in any one of the structures 1-4 characterized by the above-mentioned.

<Configuration 6>
The thickness of the said hard mask film | membrane is 1.5 nm or more and less than 15 nm. The manufacturing method of the mask blank in any one of the structures 1-5 characterized by the above-mentioned.

<Configuration 7>
The said hard mask film | membrane consists of at least one of oxygen and nitrogen, and silicon. The manufacturing method of the mask blank in any one of the structures 1-6 characterized by the above-mentioned.

<Configuration 8>
A method for manufacturing a transfer mask using a mask blank manufactured by the method for manufacturing a mask blank according to any one of configurations 1 to 7,
Forming a resist pattern on the resist film by a lithography method;
Patterning the hard mask film by dry etching using a fluorine-based gas using the resist pattern as a mask;
And a step of patterning the patterning material film by etching the patterning material film using the patterned hard mask film as a mask.

<Configuration 9>
In the film formation step, a material film containing chromium is formed as the patterning material film,
9. The transfer mask according to claim 8, wherein in the step of patterning the patterning material film, the hard mask film is used as a mask, and the chromium-containing material film is patterned by dry etching using a chlorine-based gas. Manufacturing method.

<Configuration 10>
A mask blank in which a patterning material film and a hard mask film containing silicon are formed in this order on a substrate,
The hard mask film is characterized in that a silanol group on the surface is modified with a chemical modification group by treatment with an organosilicon compound, and a water contact angle on the modified surface is 40 ° or more and less than 55 °. Mask blank to be used.

<Configuration 11>
A mask blank in which a patterning material film and a hard mask film containing silicon are formed in this order on a substrate,
In the hard mask film, the surface silanol group is modified with a chemical modification group by treatment with an organosilicon compound, and the coverage by the chemical modification group on the modified surface is set to a saturation coverage of 100%. In some cases, the mask blank is 45% or more and 85% or less.

  According to the manufacturing method of the present invention having the above-described configuration, the hard mask film is formed even immediately after the formation of the resist pattern, while ensuring the adhesion between the resist film and the hard mask film formed using the silicon-based compound. It is possible to obtain a mask blank that can be patterned with high accuracy. Further, by using a mask blank obtained by this manufacturing method, a transfer mask having a fine pattern with good shape accuracy can be obtained.

It is sectional process drawing which shows the manufacturing method of the mask blank of embodiment of this invention. It is a manufacturing process figure (the 1) which shows the manufacturing method of the transfer mask of this invention. It is a manufacturing process figure (the 2) which shows the manufacturing method of the transfer mask of this invention.

  The inventors of the present invention relate to a mask blank having a structure in which a resist film is provided on a hard mask film made of a silicon-based compound. When a hard mask pattern is formed by pattern etching of a lower hard mask film immediately after lithography. The cause of the occurrence of defects in the hard mask pattern was examined.

  As a result, it was found that the distribution of defect formation was similar to the distribution of water droplets remaining on the surface after the resist pattern was formed by lithography. As a result, water drops remaining on the surface of the process become ice due to the effect of low temperature during dry etching of the hard mask film using the resist pattern as a mask. It was estimated that the etching of the mask film was hindered. This will be described in detail as follows.

  That is, in resist pattern formation by lithography, the processed surface is spin-dried after development and rinsing. At this time, since unevenness due to the resist pattern is formed on the treated surface, fine water droplets remain between the resist patterns. Between the resist patterns, the surface of the hard mask film on which a very thin hydrophobic surface layer is formed by the surface modification treatment is exposed. For this reason, the water droplets remaining between the resist patterns rise with a large contact angle with respect to the hard mask film, and have a shape with a small surface area relative to the volume.

  Here, immediately after the resist pattern formation by lithography processing, that is, immediately after spin drying, when a pressure reduction treatment for dry etching is performed, water droplets adhering to a flat shape have a large surface area with respect to the volume, and thus in a reduced pressure environment. Evaporates easily. On the other hand, water droplets swelled with a large contact angle have poor evaporation efficiency due to their small surface area, and solidify by rapid cooling due to temperature drop in the chamber space caused by decompression and heat of vaporization from the water droplet surface. It was speculated that the ice became a foreign element during the etching of the hard mask film.

  Therefore, the inventors have not made a simple hydrophobization treatment as a surface modification treatment for a hard mask film when forming a resist film on a hard mask film composed of a silicon-based compound. As a result, it was concluded that the above-described defect can be prevented by performing the hydrophilic treatment within a range in which the evaporation (transpiration) efficiency of the water droplets remaining after the lithography treatment can be obtained. .

  Hereinafter, a detailed configuration of the present invention for obtaining the above-described effect will be described with reference to the drawings. Here, an embodiment in which the present invention is applied to a method for manufacturing a phase shift type mask blank will be described, and then an embodiment of a method for manufacturing a transfer mask using the mask blank obtained by this manufacturing method will be described. To do. In addition, in each figure, the same code | symbol is attached | subjected to the same component and it demonstrates.

≪Mask blank manufacturing method≫
FIG. 1 is a cross-sectional process diagram for explaining a method for manufacturing a mask blank according to an embodiment. Below, based on FIG. 1, the manufacturing method of the mask blank of embodiment is demonstrated.

  First, as shown in FIG. 1A, a substrate 10 is prepared, and a film forming step for forming a halftone film 11, a light shielding film 13, and a hard mask film 15 made of a silicon-based material in this order on the substrate 10 is performed. . Of these, the halftone film 11 and the light shielding film 13 are formed as patterning material films on which a fine pattern is transferred. The light shielding film 13 is formed as a material film containing chromium. Next, each component and the details of the film forming procedure will be described.

<Substrate 10>
The substrate 10 prepared here is generally made of a glass material, and a substrate made of a material containing silicon is selected. For example, if the substrate 1 is a mask blank for a binary mask or a phase shift mask, it may be made of a material that is transparent to exposure light such as ArF excimer laser light (wavelength: about 193 nm). Synthetic quartz glass is used as such a material, but aluminosilicate glass and soda lime glass can also be used. In particular, since the quartz substrate is highly transparent in an ArF excimer laser beam or in a shorter wavelength region, it can be particularly suitably used for the mask blank of the present invention.
In addition, the reflective mask blank substrate 1 is configured using low thermal expansion glass (SiO ₂ —TiO ₂ glass or the like) in which thermal expansion due to heat generation during exposure is kept low.

  The substrate 10 as described above has a peripheral end surface and a main surface polished to a predetermined surface roughness, and then subjected to a predetermined cleaning process and a drying process.

  The exposure process in lithography referred to here is an exposure process in lithography using a transfer mask produced using a mask blank. In the following, exposure light is exposure light used in this exposure process. I will do it. When the transfer mask is a binary mask or a phase shift mask, this exposure light is any of ArF excimer laser light (wavelength: 193 nm), KrF excimer laser light (wavelength: 248 nm), and i-line light (wavelength: 365 nm). Although applicable, it is desirable to apply ArF excimer laser light to exposure light from the viewpoint of miniaturization of the phase shift pattern in the exposure process. When the transfer mask is a reflective mask, EUV light (wavelength: 13.56 nm) is applied as the exposure light.

<Deposition of halftone film 11>
Next, the halftone film 11 is formed on the processing surface of the substrate 10 as described above, for example, by sputtering. The halftone film 11 formed here is formed as a material film containing, for example, silicon (Si). The halftone film 11 is preferably formed of a material containing nitrogen (N) in addition to silicon. Such a halftone film 11 can be patterned by dry etching using a fluorine-based gas, and is sufficiently etched with respect to the light-shielding film 13 formed of a material containing chromium (Cr) described below. Patterning with selectivity is possible.

  The halftone film 11 may further contain one or more elements selected from a semimetal element, a nonmetal element, and a metal element as long as patterning is possible by dry etching using a fluorine-based gas.

  Among these, the metalloid element may be any metalloid element in addition to silicon. The nonmetallic element may be any nonmetallic element in addition to nitrogen. For example, the nonmetallic element contains one or more elements selected from oxygen (O), carbon (C), fluorine (F), and hydrogen (H). And preferred. Metal elements include molybdenum (Mo), tungsten (W), titanium (Ti), tantalum (Ta), zirconium (Zr), hafnium (Hf), niobium (Nb), vanadium (V), cobalt (Co), Examples are chromium (Cr), nickel (Ni), ruthenium (Ru), tin (Sn), boron (B), and germanium (Ge).

  Examples of the halftone film 11 containing such an element include those made of MoSiN.

  The halftone film 11 has a refractive index n, an extinction coefficient k, and a film thickness set so as to have a predetermined phase difference and a predetermined transmittance with respect to the exposure light, and the refractive index n and the extinction coefficient. The film is formed by adjusting the composition of the film material and the film forming conditions so as to be k. As an example, when the exposure light is ArF excimer laser light, the phase difference is, for example, 150 [deg] to 180 [deg], and the transmittance is 1% to 30%.

  In forming the halftone film 11 by sputtering, a sputtering target and a sputtering gas containing the material constituting the halftone film 11 at a predetermined composition ratio are used, and argon (Ar) and helium as necessary. Film formation is performed using an inert gas such as (He) as a sputtering gas.

  After the halftone film 11 is formed by sputtering, an annealing process at a predetermined heating temperature is performed as a post process.

<Deposition of light shielding film 13>
Next, a light shielding film 13 is formed on the halftone film 11 by sputtering, for example. The light shielding film 13 is a material film containing chromium and may be formed as a single layer, and has a two-layer structure of a lower layer 13a and an upper layer 13b as illustrated. A film may be formed, or a plurality of layers may be formed. When forming the light-shielding film 13 as a plurality of layers, the respective layers with different chromium (Cr) contents are formed.

  Here, the chromium-based thin film uses a mixed gas of oxygen mainly composed of chlorine as an etching gas at the time of patterning, but the hard mask film 15 made of a silicon-based material to be formed next is in contrast to the chlorine-based gas. Has strong etching resistance. For this reason, when etching the light-shielding film 13 composed of a chromium-based thin film using the hard mask film 15 made of a silicon-based material as a mask, patterning etching can be performed with high etching selectivity.

  The light shielding film 13 may contain a material containing one or more elements selected from oxygen, nitrogen, carbon, boron, hydrogen, and fluorine in addition to chromium metal. Further, the light shielding film 13 is made of indium (In), tin (Sn), and molybdenum (Mo) for the purpose of suppressing the decrease in the etching rate of the entire film while maintaining the optical density (OD). It may contain at least one selected metal element (metal element such as indium).

  Such a light shielding film 13 can be patterned by dry etching using an oxygen-containing chlorine-based gas. The light-shielding film 13 has sufficient etching selectivity with the halftone film 11 formed of a material containing silicon (Si), and light-shields without damaging the halftone film 11. It is possible to remove the film 13 by etching. The light shielding film 13 has sufficient etching selectivity with respect to a hard mask film 15 formed of a material containing silicon (Si), which will be described below, and the light shielding using the hard mask film 15 as a mask. Patterning of the film 13 is possible.

  Further, the light shielding film 13 as described above has a composition accuracy of each layer such that the shape accuracy in dry etching is ensured and the optical density (OD) is higher than a predetermined value with respect to the exposure light used in the exposure transfer process. The film is formed by setting the film thickness.

  In the formation of the light shielding film 13 by the sputtering method, a sputtering target containing a material constituting each layer of the light shielding film 13 in a predetermined composition ratio and a sputtering gas are used, and if necessary, argon (Ar) and helium ( Film formation is performed using an inert gas such as He) as a sputtering gas.

<Deposition of Hard Mask Film 15>
Next, a hard mask film 15 is formed on the light shielding film 13 by sputtering, for example. The hard mask film 15 formed here is a film containing silicon (Si), and is extremely thin enough to function as an etching mask until dry etching for forming a pattern on the light shielding film 13 is completed. The film is formed with a film thickness.

  Such a hard mask film 15 contains one or more elements selected from oxygen (O), nitrogen (N), carbon (C), boron (B) and hydrogen (H) in addition to silicon (Si). A film is formed using a material to be formed.

Among these, it is preferable to form the hard mask film 15 made of at least one of oxygen (O) and nitrogen (N) together with silicon (Si). Specific examples of the material constituting the hard mask film 15 include silicon oxide (SiO ₂ ), silicon nitride (SiN), and silicon oxynitride (SiON). The hard mask film 15 made of these materials has a sufficient etching selectivity with respect to the light shielding film 13 formed of a material containing chromium (Cr), and almost damages the light shielding film 13. Instead, the hard mask film 15 can be removed by etching.

  The hard mask film 15 made of these materials is an extremely thin film because it has a sufficient etching selectivity with respect to the light shielding film 13 formed of a material containing chromium (Cr) as a lower layer. Also sufficiently function as an etching mask. Therefore, the film is formed with a film thickness of 1.5 nm to less than 15 nm.

  In the formation of the hard mask film 15 by sputtering, a sputtering target and a sputtering gas containing the material constituting the hard mask film 15 at a predetermined composition ratio are used, and argon (Ar) and helium as necessary. Film formation is performed using an inert gas such as (He) as a sputtering gas.

  The surface S of the hard mask film 15 formed here is covered with a silanol group in which a hydroxyl group (—OH) is bonded to silicon (Si) constituting the hard mask film 15, thereby forming a hydrophilic surface and It has become.

<Modification process>
Next, as shown in FIG. 1B, a modification treatment step of modifying the silanol group on the surface S of the hard mask film 15 with a chemical modification group is performed by a treatment using an organosilicon compound. It is important that this reforming process is performed so that the water contact angle of the surface S of the hard mask film 15 is not less than 40 ° and not more than 55 ° at a room temperature of 23 ° C.

  The organosilicon compound used in the modification treatment step is hydrophobic with excellent affinity between the functional group capable of binding to the silanol group (—SiOH) on the surface S of the hard mask film 15 and the resist film formed in the next step. And a compound having a functional group of

  Examples of the functional group that can be bonded to the silanol group (—SiOH) include an amino group, a hydroxyl group, and a chloride group, and an amino group and a hydroxyl group are preferably exemplified.

  The functional group having excellent affinity with the resist film can be determined as appropriate depending on the components of the resist material constituting the resist film. For example, a chemical bond such as a covalent bond or hydrogen bond with the resist material. Functional group that binds by hydrophobic-hydrophobic interaction or the like is selected.

  For example, examples of the functional group chemically bonded to the resist material include an alkyl sulfonic acid group, an alkyl amine group, and an alkyl carboxylic acid group. Moreover, an alkyl group is illustrated as a functional group couple | bonded with a resist material by hydrophobic-hydrophobic interaction.

  Specific examples of the organosilicon compounds having the functional groups as described above include 1,1,3,3-tetramethyldisilazane, hexamethyldisilazane (HMDS), vinyltrimethylsilane, hexamethyldisilane, methylsilane, and dimethyl. Examples include silane, trimethylsilane, diethylsilane, propylsilane, phenylsilane, vinyltriethoxysilane, tetramethoxysilane, phenyltriethoxysilane, methyltriethoxysilane, and octamethylcyclotetrasiloxane.

  Of these organosilicon compounds, hexamethyldisilazane (HMDS) is preferably used. Hexamethyldisilazane (HMDS) is an amine compound substituted with a trimethylsilyl group [—Si (CH 3) 3], and amino as a functional group capable of binding to the silanol group (—SiOH) on the surface S of the hard mask film 15. And a methyl group that binds to the resist material by a hydrophobic-hydrophobic interaction as a functional group having an affinity for the resist film.

  According to such a modification treatment process using hexamethyldisilazane (HMDS), the silanol group (—SiOH) on the surface S of the hard mask film 15 reacts with hexamethyldisilazane (HMDS), and silanol The trimethylsilyl group [—Si (CH 3) 3] of hexamethyldisilazane (HMDS) is bonded to the group (—SiOH) as a chemical modification group. Thereby, a trimethylsilyl group [—Si (CH 3) 3] is bonded to the surface of the hard mask film 15 originally containing silicon (Si). For this reason, the surface modification process of the hard mask film 15 is performed with almost no change in film quality other than the degree of hydrophobicity. Such a modification process similarly proceeds on the surface to which hexamethyldisilazane (HMDS) is supplied in the substrate 10 made of a material containing silicon. In addition, ammonia generated by this reaction is quickly discharged as ammonia gas.

  The modification process using the organosilicon compound as described above is performed by supplying the organosilicon compound to the surface S of the hard mask film 15.

  In such a modification treatment step, the chemical modification group is bonded to the silanol group by controlling at least one of the treatment time, the supply flow rate of the organosilicon compound to the surface S of the hard mask film 15, and the treatment temperature. Adjust the amount. Thereby, the water contact angle of the surface S of the hard mask film 15 is set to a range of 40 ° to 55 ° at a room temperature of 23 ° C. Moreover, you may implement this modification | reformation process process and the coverage by the chemical modification group with respect to a silanol group as 45 to 85% of range, when a saturation coverage is 100%. The water contact angle can be measured with a contact angle meter. Moreover, the coverage by a chemical modification group can be measured with the mass spectrometer (for example, TOF-SIMS) which can measure the ion etc. of a chemical modification group directly or indirectly.

<Deposition of resist film 17>
Next, as shown in FIG. 1C, a resist film 17 is formed on the surface S of the hard mask film 15 that has been modified by the bonding of chemical modification groups. For the formation of the resist film 17, for example, a resist material layer is formed by a coating method such as a spin coating method, and a subsequent process is performed. The material of the resist film 17 formed here is not particularly limited. However, since it is effective when forming a fine pattern, it is preferably applied to a chemically amplified resist. Further, it can be applied to both negative and positive resists, but it is effective when applied to a negative resist.

  As described above, the mask blank 1 in which the halftone film 11, the light shielding film 13, the hard mask film 15, and the resist film 17 are laminated in this order on the substrate 10 is obtained.

≪Method for manufacturing transfer mask≫
2 and 3 are cross-sectional process diagrams for explaining the method for manufacturing the transfer mask according to the embodiment. The transfer mask manufacturing method shown in these drawings is a transfer mask manufacturing method using the halftone mask blank 1 obtained by the manufacturing method described with reference to FIG. Below, based on FIG. 2 and FIG. 3, the manufacturing method of the transfer mask is demonstrated. 2 and 3, the same components as those described with reference to FIG. 1 are denoted by the same reference numerals, and redundant description is omitted.

<Formation of resist pattern>
First, as shown in FIG. 2A, a first resist pattern 17a is formed on the resist film 17 by lithography. Here, first, a phase shift pattern and an alignment mark pattern to be formed on the halftone film 11 are exposed and drawn on the resist film 17 in the mask blank 1. An electron beam is often used for this exposure drawing. At this time, the central portion of the substrate 10 is used as a phase shift pattern forming region 10a, and a pattern corresponding to the phase shift pattern is exposed and drawn. In addition, in the outer peripheral region 10b of the phase shift pattern forming region 10a, a pattern such as an alignment mark is exposed and drawn without forming a phase shift pattern.

  Thereafter, PEB processing, development processing, rinsing processing, and spin drying processing are performed on the resist film 17. Thereby, a first resist pattern 17a having a phase shift pattern and an alignment mark pattern is formed.

<Patterning of hard mask film 15>
Next, as shown in FIG. 2B, in the decompression chamber, the hard mask film 15 is dry-etched using a fluorine-based gas using the first resist pattern 17a as a mask, and the hard mask film 15 is patterned to form a hard mask pattern. 15a is formed. Thereafter, the first resist pattern 17a is removed. Here, the light-shielding film 13 may be dry-etched with the first resist pattern 17a remaining without being removed. Even in this case, the first resist pattern 17 a disappears during the dry etching of the light shielding film 13.

<Patterning of Halftone Film 11 and Light-shielding Film 13>
Next, as shown in FIG. 2C, dry etching of the light-shielding film 13 using a mixed gas of chlorine-based gas and oxygen gas (oxygen-containing chlorine-based gas) is continued using the hard mask pattern 15a as a mask in the decompression processing chamber. Then, the light shielding film 13 containing a metal element such as indium together with chromium is patterned. As a result, the light shielding film 13 is etched with extremely high etching selectivity with respect to the hard mask film 15 containing silicon to form the light shielding film pattern 13aa.

  Thereafter, as shown in FIG. 2D, the halftone film 11 using fluorine gas is dry-etched using the light shielding film pattern 13aa as a mask to pattern the halftone film 11 formed of a material containing silicon. Thereby, the phase shift pattern 20a formed by patterning the halftone film 11 is formed in the phase shift pattern forming region 10a of the substrate 10. In addition, a hole-shaped alignment mark pattern 20 b penetrating the light shielding film 13 and the halftone film 11 is formed in the outer peripheral region 10 b of the substrate 10. In the dry etching of the halftone film 11 formed of such a material containing silicon, the hard mask pattern 15a formed of the material containing silicon is also removed at the same time.

  Next, as shown in FIG. 3E, a second resist pattern 31 is formed so as to cover the outer peripheral region 10b of the substrate 10. At this time, first, a resist film is formed on the substrate 10 by a spin coating method. Next, the resist film is exposed so that the resist film remains in a shape covering the outer peripheral region 10b of the substrate 10, and then a predetermined process such as a development process is performed on the resist film. Thus, the second resist pattern 31 is formed in a shape that covers the outer peripheral region 10b of the substrate 10.

  Thereafter, as shown in FIG. 3F, the second resist pattern 31 is used as a mask to perform dry etching of the light shielding film 13 using a mixed gas of chlorine-based gas and oxygen gas to form a light shielding film in a strip shape covering the outer peripheral region 10b. A light shielding pattern 20c formed by patterning 13 is formed.

  Next, as shown in FIG. 3G, the second resist pattern 31 is removed, and a predetermined process such as cleaning is performed. Thus, the transfer mask 2 is obtained.

<< Effects of Embodiment >>
According to the mask blank manufacturing method of the embodiment described above, the water contact angle on the surface of the hard mask film 15 containing silicon is set to 40 ° or more, so that the hard mask film 15 that is hydrophilic at the time of film formation is formed. The surface of the film is appropriately hydrophobized, and adhesion with the resist film 17 can be ensured. And according to the manufacturing method of the transfer mask using the mask blank 1 produced by this manufacturing method, as explained using FIG. 2A, the pattern when the first resist pattern 17a is formed by the lithography process It becomes possible to prevent the fall.

  On the other hand, when the water contact angle is less than 40 °, that is, when the modification treatment is insufficient, the hydrophilicity of the surface of the hard mask film 15 is too high, so that it is difficult to ensure adhesion with the resist film 17. Therefore, pattern collapse cannot be prevented. For example, in the modification process of the hard mask film 15 when hexamethyldisilazane (HMDS) is used as the organosilicon compound, it is difficult to control the water contact angle within a range of less than 40 ° from the process speed. . Therefore, control in a range of 40 ° or more is possible.

  Furthermore, according to the mask blank manufacturing method of the embodiment, the water contact angle on the surface of the hard mask film 15 is set to 55 ° or less, thereby preventing the surface of the hard mask film 15 from being excessively hydrophobized. The height of water droplets remaining on the hard mask film 15 is limited, and a surface area can be secured. Therefore, even if water drops remain, the evaporation (transpiration) efficiency can be ensured. And according to the manufacturing method of the transfer mask using the mask blank 1 manufactured by this manufacturing method, even if water droplets remain between the first resist patterns 17a after the lithography processing described with reference to FIG. 2A. In the decompression process during the dry etching of the hard mask film 15 described with reference to FIG. 2B, the water droplets can be evaporated and removed without being iced.

  On the other hand, when the water contact angle exceeds 55 °, the height of the attached water droplets becomes high, so that the water droplets hardly evaporate and remain on the processing surface. It remains as a foreign object.

  As a result, according to the mask blank manufacturing method and the subsequent transfer mask manufacturing method for performing the modification processing described in the embodiment, the resist pattern 17 is formed on the resist film 17 by lithography as shown in the following examples. Can be efficiently evaporated without icing the water droplets remaining between the resist patterns after the lithography process, thereby preventing the pattern collapse when forming the hard mask film 15 using the resist pattern as a mask. This etching can be performed with good shape accuracy.

  In addition, in the above, the manufacturing method of the halftone type mask blank was illustrated as embodiment of the manufacturing method of the mask blank 1. FIG. However, the mask blank manufacturing method of the present invention is widely applicable to a mask blank manufacturing method having a step of forming a resist film 17 in contact with the silicon-containing hard mask film 15 and obtains the same effect. Is possible.

  As such an example, a binary mask blank can be exemplified. When the present invention is applied to a method for manufacturing a binary type mask blank, a light shielding film using, for example, a chromium-based material is formed on the substrate 10, and a hard mask film containing silicon is formed thereon. The modification process described above may be performed on the surface of the hard mask film, and the same effect can be obtained.

  Hereinafter, the embodiment of the present invention will be described more specifically with reference to examples.

Example 1
[Manufacture of mask blanks]
The mask blank 1 according to the first embodiment described with reference to FIG. 1 was manufactured as follows. First, as shown in FIG. 1A, a translucent substrate 10 made of synthetic quartz glass having a main surface dimension of about 152 mm × about 152 mm and a thickness of about 6.25 mm was prepared. The substrate 10 has a peripheral end surface and a main surface S polished to a predetermined surface roughness and then subjected to a predetermined cleaning process and a drying process.

  Next, the halftone film 11, the lower layer 13a of the light shielding film 13, the upper layer 13b of the light shielding film 13, and the hard mask film 15 were formed in this order on the substrate 10 by sputtering. For sputtering film formation, a DC sputtering type single wafer type film formation apparatus was used. The material configuration and film thickness of each layer are as follows.

Halftone film 11: MoSiN, film thickness 69 nm
Lower layer 13a: CrON, film thickness 47nm
Upper layer 13b: CrN, film thickness 5 nm
Hard mask film 15: SiON, film thickness 5 nm

  After the halftone film 11 was formed by sputtering, an annealing process was performed at 450 ° C. for 30 minutes as a post-treatment after the film formation. With respect to the halftone film 11 after the annealing treatment, the transmittance and the phase difference with respect to the wavelength (about 193 nm) of the ArF excimer laser beam were measured with a phase shift amount measuring device. The transmittance was 6.4% and the phase difference was 175 °. Met.

After the above sputter deposition, as shown in FIG. 1B, the surface of the hard mask film 15 was subjected to a modification process using hexamethyldisilazane (HMDS) as the organosilicon compound. Here, the modification process was performed on each of the plurality of samples 1 to 12 under various processing conditions in which the processing time and the supply amount of hexamethyldisilazane (HMDS) were changed. This adjusted the water contact angle of the surface S of the hard mask film | membrane 15 in each sample 1-12. At this time, in the preparation of the sample 11, the modification treatment was performed under the condition that the modification with the chemical modification group on the surface of the hard mask film 15 was saturated. Further, in the production of the sample 12, the modification process was not performed. The chemical modification group is a trimethylsilyl group [Si (CH ₃ ) ₃ ].

  Table 1 below shows the water contact angle of the surface of the hard mask film 15 after the modification treatment in each of the samples 1 to 12. The water contact angle on the surface of the hard mask film 15 was measured in a room temperature 23 ° C. atmosphere using a fully automatic contact angle meter DM-701 manufactured by Kyowa Interface Chemical Co., Ltd.

In Table 1 below, the coverage by the chemical modification group [hexamethyldisilazane (HMDS)] after the modification treatment in each of the samples 1 to 12, and the coverage of the sample 11 as the saturation coverage 100 It was shown as a relative value.
The coverage with the chemically modifying group [hexamethyldisilazane (HMDS)] was determined as follows.

  First, in each sample 1 to sample 12, the silanol group remaining on the surface of the hard mask film 15 was sufficiently chemically modified with a silicon compound group containing bromine. Next, each sample 1 to sample 12 was subjected to surface analysis using TOF-SIMS, and the detection intensity A of secondary ions derived from the silicon compound group containing bromine was measured. Then, the detection intensity A of the sample 12 not subjected to the modification treatment is set as a reference value B, and (reference value B−detection intensity A) / reference value B is determined as hexamethyldisilazane (HMDS) in each of the samples 1 to 12. And the calculated coverage was converted to a relative value with the coverage of sample 11 as 100.

  Next, as shown in FIG. 1C, a chemically amplified negative resist (SLN-009 + manufactured by Fuji Film Electronics Materials Co., Ltd.) is spin-coated on the hard mask film 15 and then dried to obtain a resist having a thickness of 80 nm. A film 17 was formed.

  By the above procedure, the mask blank 1 having a structure in which the halftone film 11, the light shielding film 13 having a two-layer structure, the hard mask film 15, and the resist film 17 are laminated in this order on the substrate 10 was manufactured.

[Patterning of hard mask film 15]
Next, a predetermined device pattern was drawn on the resist film 17 using an electron beam drawing machine. Here, a pattern corresponding to the phase shift pattern to be formed on the halftone film 11 and including a line and space is drawn as the device pattern. The drawing here was intended to form a 40 nm wide line-and-space phase shift pattern corresponding to the pattern size of the SRAF pattern.

  Next, the resist film 17 was subjected to a development process using a 2.38% TMAH (tetramethylammonium hydride) aqueous solution as a developer, and then rinsed with pure water (ion-exchanged water).

  The substrate with a resist pattern after the rinse treatment was spin-dried. At this time, the rotation speed was 1500 rpm and the drying time was 400 seconds. Thus, a first resist pattern 17a (see FIG. 2A) formed by patterning the resist film 17 was completed.

  Next, using the first resist pattern 17a as a mask, the hard mask film 15 was dry etched to form a hard mask pattern 15a (see FIG. 2B). In dry etching, fluorine-based gas (SF6) was used as an etching gas, and the etching time was 20 seconds.

[Evaluation of hard mask pattern]
The shape of the hard mask pattern 15a formed as described above was evaluated. Here, the number of defects due to the remaining pattern among the defective defects formed in the hard mask pattern 15a, that is, the defective etching of the hard mask film 15 using the first resist pattern 17a as a mask, was counted. The results are shown in Table 1 below. The number of defects was counted using a mask blank defect inspection apparatus (MAGICS series M2351) manufactured by Lasertec Corporation.

  As shown in Table 1, Sample 1 to Sample 7 in which the water contact angle after the modification treatment on the surface of the hard mask film 15 is in the range of 40 ° to 55 ° and the coverage by the chemical modification group is 45% to 85%. Then, the number of defects of the hard mask pattern 15a is suppressed to 50 or less. On the other hand, Sample 8 to Sample 11 in which the water contact angle and the coverage by the chemical modifying group are out of the above ranges have 200 or more defects. In Sample 12, since the surface of the hard mask film 15 was not subjected to the modification treatment, pattern collapse occurred in the first resist pattern 17a, and thus the hard mask film 15a was not dry etched.

  From the above results, it was confirmed that by applying the present invention, a mask blank 1 capable of patterning the hard mask film 15 formed using a silicon-based compound with high accuracy was obtained. Further, by using the hard mask pattern 15a formed by patterning the hard mask film 15 with high accuracy as a mask, the light shielding film 13 and the halftone film 11 can be etched with good shape accuracy. It was confirmed that a transfer mask having a fine pattern with good shape accuracy was obtained.

DESCRIPTION OF SYMBOLS 1 ... Mask blank 2 ... Transfer mask 10 ... Substrate,
11 ... Halftone film (patterning material film)
13 ... Light-shielding film (patterning material film, chromium-containing material film)
DESCRIPTION OF SYMBOLS 15 ... Hard mask film | membrane 17 ... Resist film 17a ... 1st resist pattern 31 ... 2nd resist pattern d ... Film thickness of a hard mask film | membrane

Claims (11)

A film forming process for forming a patterning material film and a silicon-containing hard mask film on the substrate in this order;
A modification treatment step of modifying a silanol group on the surface of the hard mask film with a chemical modification group by treatment with an organosilicon compound;
Forming a resist film on the modified hard mask film,
The said modification process is performed so that the water contact angle of the surface of the said hard mask film | membrane in room temperature 23 degreeC may be in the range of 40 degrees or more and 55 degrees or less. A film forming process for forming a patterning material film and a silicon-containing hard mask film on the substrate in this order;
A modification treatment step of modifying a silanol group on the surface of the hard mask film with a chemical modification group by treatment with an organosilicon compound;
Forming a resist film on the modified hard mask film,
The said modification process performs a process so that the coverage by the said chemical modification group of the said silanol group may be in the range of 45% or more and 85% or less when a saturated coverage is 100%. Mask blank manufacturing method . 3. The method of manufacturing a mask blank according to claim 1, wherein in the film forming step, a material film containing chromium is formed as the patterning material film. The said organosilicon compound has an amine. The manufacturing method of the mask blank in any one of Claims 1-3 characterized by the above-mentioned. The said organosilicon compound is hexamethyldisilazane. The manufacturing method of the mask blank in any one of Claims 1-4 characterized by the above-mentioned. The thickness of the said hard mask film | membrane is 1.5 nm or more and less than 15 nm. The manufacturing method of the mask blank in any one of Claims 1-5 characterized by the above-mentioned. The method for manufacturing a mask blank according to claim 1, wherein the hard mask film is made of at least one of oxygen and nitrogen and silicon. It is a manufacturing method of the mask for transfer using the mask blank manufactured by the manufacturing method of the mask blank in any one of Claims 1-7,
Forming a resist pattern on the resist film by a lithography method;
Patterning the hard mask film by dry etching using a fluorine-based gas using the resist pattern as a mask;
And a step of patterning the patterning material film by etching the patterning material film using the patterned hard mask film as a mask. In the film formation step, a material film containing chromium is formed as the patterning material film,
9. The transfer material according to claim 8, wherein, in the step of patterning the patterning material film, the material film containing chromium is patterned by dry etching using a chlorine-based gas using the hard mask film as a mask. Mask manufacturing method. A mask blank in which a patterning material film and a hard mask film containing silicon are formed in this order on a substrate,
The hard mask film is characterized in that a silanol group on the surface is modified with a chemical modification group by treatment with an organosilicon compound, and a water contact angle on the modified surface is 40 ° or more and less than 55 °. Mask blank to be used. A mask blank in which a patterning material film and a hard mask film containing silicon are formed in this order on a substrate,
In the hard mask film, the surface silanol group is modified with a chemical modification group by treatment with an organosilicon compound, and the coverage by the chemical modification group on the modified surface is set to a saturation coverage of 100%. In some cases, the mask blank is 45% or more and 85% or less.

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