JPWO2016129225A1 - SUBSTRATE WITH THIN FILM LAYER FOR PATTERN FORMING MASK AND METHOD FOR PRODUCING PATTERNED SUBSTRATE - Google Patents

Abstract

Kind Code: A1 A substrate with a thin film layer for a pattern forming mask and a method for producing a patterned substrate using the substrate with a thin film layer for a pattern forming mask, capable of forming an uneven pattern with high processing accuracy on the surface of the substrate by dry etching. I will provide a. A substrate made of silicon or a silicon-based compound, and a thin film that is patterned on the surface of the substrate by etching using plasma of a mixed gas of oxygen and chlorine and used as a mask for pattern formation In the substrate with a thin film layer for a pattern forming mask comprising the layers, the thickness of the thin film layer is plotted as the vertical axis and the chromium content in the thin film layer is varied as the horizontal axis, and the chromium content is 40 atomic% or more. The use of a thin film layer made of chromium oxide of 50 atomic% or less and having a thickness of 10 nm or less is excellent in LER and side wall angle after quartz dry etching and can secure resistance as an etching mask. It is valid.

Description

  The present invention relates to a substrate with a thin film layer for a pattern forming mask in which a thin film layer for a mask which is used as a mask pattern at the time of pattern formation is provided on a surface on which a pattern is formed. The present invention relates to a method for manufacturing a substrate.

  In recent years, microfabrication technology associated with high integration of large-scale integrated circuits has become extremely important. In recent years, in the field of semiconductor microfabrication technology, UV (Ultra Violet) nanoimprint lithography, which does not require apparatus costs, is attracting attention from the viewpoint of production cost. Conventional photolithography generally uses a photomask in which a light-shielding fine pattern made of a metal thin film or the like is provided on a light-transmitting glass substrate (Patent Document 1, etc.). On the other hand, in the nano nanoimprint lithography, a nano imprint template in which a fine uneven pattern is formed on the surface of a substrate that transmits UV light (ultraviolet light) is used (Patent Documents 2, 3, etc.).

  As a nanoimprint template used for manufacturing such a semiconductor device, a mask blank provided with a hard mask layer on a quartz substrate, which is used for manufacturing a photomask, can be similarly used. Specifically, after forming a resist pattern on the hard mask layer of the mask blank, using the resist pattern as a mask, the hard mask layer is etched to form a mask pattern, and then quartz is etched using the mask pattern. It can produce by doing.

  With the demand for higher integration of semiconductor circuits, the dimensions of nanoimprint template patterns are required to be further miniaturized. With the miniaturization of pattern dimensions, it is necessary to improve the processing accuracy in etching quartz substrates. It has become.

  Moreover, not only for the manufacture of semiconductor devices, but also for optical components with optical functions added by fine patterns such as gratings, pattern dimensions and accuracy less than the wavelength of the target light are required. Improvement in processing accuracy in etching is also required in the production of imprint templates and optical components themselves.

  From the viewpoint of the etching ratio, a chromium compound containing chromium is mainly used as a hard mask for etching a quartz substrate. In Patent Documents 1 to 3, mask blanks having a chromium compound layer on a quartz substrate are used. Is disclosed.

JP 2007-33470 A JP 2011-207163 A JP 2008-209873 A

  The processing accuracy in the etching of quartz largely depends on the film quality of the hard mask layer. Specifically, it has been revealed by the inventors that the processing accuracy of the finished pattern varies greatly depending on the composition.

  Patent Document 1 discloses a mask blank provided with a hard mask layer in the form of a laminated film of a chromium metal layer and a chromium compound layer. Since Patent Document 1 is intended to produce a photomask, it is assumed that the hard mask layer has a light shielding property, and it is necessary to increase the thickness of the entire hard mask layer as compared with the case where the light shielding property is not assumed. There is. In order to ensure the light shielding property, it is considered that the thickness of the entire hard mask layer needs to be 30 nm or more. In addition, Patent Document 1 does not describe etching of quartz because a photomask is manufactured by patterning a hard mask layer.

Patent Document 3 also presupposes that the hard mask layer has a light-shielding property because it mainly aims to produce a photomask. Patent Document 3 discloses a hard mask layer having a laminated structure of a layer containing 60 at% or more of oxygen containing chromium as a main component and a layer containing tantalum, hafnium, or zirconium as a main component. A hard mask layer including a layer mainly composed of tantalum, hafnium, or zirconium has a problem of high cost.
In addition, when the layer containing chrome as a main component contains oxygen of 60 at% or more, it is clear from the examination by the present inventors that it cannot be said to have sufficient etching resistance as a mask for dry etching of quartz. It has become.

  Patent Document 2 discloses a mask blank provided with a hard mask layer made of CrOxNyCz (where x> 0) as a chromium compound. However, Patent Document 2 does not show a suitable composition range in which high processing accuracy can be obtained when a hard mask layer made of CrOxNyCz (where x> 0) is dry-etched.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a substrate with a thin film layer for a pattern forming mask, which can form a concavo-convex pattern with high processing accuracy on the surface of the substrate by dry etching. And Another object of the present invention is to provide a method for producing a patterned substrate using a substrate with a thin film layer for a pattern forming mask.

The substrate with a thin film layer for a pattern forming mask of the present invention comprises a substrate made of silicon or a silicon-based compound,
Patterned by etching using plasma of a mixed gas of oxygen and chlorine provided on the surface of the substrate, and a thin film layer used as a mask for pattern formation.
A thin film layer consists of chromium oxide whose chromium content rate is 40 atomic% or more and 50 atomic% or less, and has a thickness of 10 nm or less.

The method for producing a patterned substrate of the present invention comprises a substrate made of silicon or a silicon-based compound and a chromium oxide provided on the surface of the substrate and having a chromium content of 40 atomic% to 50 atomic%. A substrate with a thin film layer for a pattern forming mask provided with a thin film layer having the following thickness is prepared:
A mask layer for patterning is formed on the thin film layer,
The mask layer is used to pattern the thin film layer by performing an etching process using plasma of a mixed gas of oxygen and chlorine,
This is a method for manufacturing a patterned substrate in which the surface of the substrate is patterned by performing an etching process using plasma containing a fluorine-based gas using the patterned thin film layer as a mask.

  The method for producing a patterned substrate of the present invention is suitable when the pattern line width in patterning includes a portion of 50 nm or less, and more preferably when the pattern line width includes a portion of 30 nm or less.

In the method for producing a patterned substrate of the present invention, the ratio of oxygen to chlorine in the mixed gas of oxygen and chlorine is preferably 0.05 to 0.40.
Here, the ratio of oxygen and chlorine is a flow rate ratio of oxygen and chlorine (oxygen / chlorine) introduced into the etching apparatus.

  Moreover, it is preferable that the fluorine-containing gas content rate in the plasma containing a fluorine-containing gas shall be 50% or less. Here, the fluorine-based gas means a gas containing at least fluorine as a constituent element such as a fluorocarbon gas and a sulfur hexafluoride gas, and any one kind of fluorine-based gas is contained in the plasma. There may be a plurality of fluorine-based gas species.

  The patterning mask layer may be formed by applying a resist film on the thin film layer and forming an uneven pattern on the resist film by an imprint method.

  As the patterned substrate, for example, a nanoimprint template or an optical element can be manufactured. The nano-imprint template includes a master template or a sub-master template that is produced by transferring an uneven pattern by an imprint method using the master template.

  The substrate with a thin film layer for a pattern forming mask of the present invention is a thin film having a thickness of 10 nm or less made of chromium oxide having a chromium content of 40 atomic% to 50 atomic% on a base made of silicon or a silicon-based compound. Therefore, if the thin film layer is patterned by etching using plasma of a mixed gas of oxygen and chlorine, a mask pattern with extremely high processing accuracy can be formed. As a result, the surface of the substrate It is possible to form a concavo-convex pattern with high processing accuracy.

  Further, in the method for producing a patterned substrate of the present invention, the thin film layer of the substrate with a thin film layer for a pattern forming mask of the present invention is patterned by an etching process using plasma of a mixed gas of oxygen and chlorine. A mask pattern with high accuracy can be obtained, and then the substrate is etched using the patterned thin film layer as a mask to obtain a patterned substrate having a concavo-convex pattern with high processing accuracy.

It is sectional drawing of the base | substrate with a thin film layer for pattern formation masks of 1st Embodiment. It is sectional drawing of the base | substrate with a thin film layer for pattern formation masks of 2nd Embodiment. It is a figure which shows the process of producing a patterned base | substrate from the base | substrate with a thin film layer for pattern formation masks of 1st Embodiment. It is a figure which shows the process of producing a patterned base | substrate from the base | substrate with a thin film layer for pattern formation masks of 2nd Embodiment. It is a figure which shows the process of forming a resist pattern by the nanoimprint method on the base | substrate with a thin film layer for pattern formation masks. It is a figure which shows schematic structure of the etching apparatus of one Embodiment which implements the etching method of this invention. It is a figure which shows the content rate profile in the depth direction of the content element of a thin film layer. It is the figure which plotted the Example and the comparative example by making the thickness of a thin film layer into a vertical axis | shaft, and the chromium content rate in a thin film layer as a horizontal axis.

  Hereinafter, although an embodiment of the present invention is described using a drawing, the present invention is not limited to this. In addition, in order to make it easy to visually recognize, the scale of each component in the drawings is appropriately changed from the actual one.

<Substrate with Thin Film Layer for Pattern Formation Mask of First Embodiment>
FIG. 1 is a cross-sectional view of a substrate 1 with a thin film layer for a pattern forming mask according to a first embodiment of the present invention.
The substrate 1 with a thin film layer for a pattern forming mask according to this embodiment is patterned by an etching process using a base 40 made of silicon or a silicon-based compound and a plasma of a mixed gas of oxygen and chlorine provided on the surface of the base 40. And a thin film layer 50 used as a mask for pattern formation. The thin film layer 50 is made of chromium oxide having a chromium content of 40 atomic% to 50 atomic% and has a thickness of 10 nm or less. Is.

The substrate 40 is a substrate having a pattern formation surface on which a fine uneven pattern is formed. In FIG. 1, the substrate 40 is a flat substrate.
Examples of the silicon compound constituting the substrate 40 include SiO ₂ and SiON. In view of the etching ratio with the thin film layer 50 made of chromium oxide, those made of synthetic quartz containing SiO ₂ as a main component are particularly preferable. Here, the main component is a component that occupies 90% or more of all components.

  The thin film layer 50 is made of chromium oxide. If the chromium content in the entire layer is 40 atomic% or more and 50 atomic% or less, the chromium content is less than 40 atomic% depending on the position in the depth direction. Or more than 50 atomic%. The chromium content of the entire layer is determined by performing X-ray photoelectron spectroscopy while performing Ar etching from the surface of the layer in the depth direction, measuring the depth dependence of the element content for each element, and calculating the element content by The ratio of values integrated in the depth direction is defined as the content (atomic%) of each element in the film, and the chromium content (atomic%) of the entire film is obtained.

  The thin film layer 50 does not need to have light shielding properties, and the thickness of the thin film layer 50 is preferably 10 nm or less. The thickness is preferably 0.5 nm or more, more preferably 2.5 nm or more. Here, the thickness of the thin film layer is a thickness measured by processing the substrate with a focused ion beam and observing the processed cross section with a transmission electron microscope.

  The substrate 1 with a thin film layer for a pattern forming mask according to this embodiment can be used, for example, for producing a master template for nanoimprinting. When applied to the optical imprinting method, the substrate 40 is used for imprinting. Must be transparent to the light produced. For example, when applied to an imprint method having a step of curing a resist with UV light, it is preferable that the resist is transparent to at least UV light.

  The substrate of the substrate with a thin film layer for a pattern forming mask of the present invention is not limited to a flat substrate, and is not particularly limited as long as it is made of silicon or a silicon-based compound having a surface on which an uneven pattern is to be formed. Absent. The surface on which the concavo-convex pattern is to be formed is not limited to a flat surface, and may be a curved surface. For example, an optical member such as a concave lens or a convex lens may be used as a base. In the case of producing an optical member, a base made of a material transparent to visible light is generally used.

<Substrate with Thin Film Layer for Pattern Formation Mask of Second Embodiment>
FIG. 2 is a cross-sectional view of the substrate 2 with a thin film layer for pattern formation mask according to the second embodiment. In the present embodiment, a base 10 having a counterbore part 11 is provided on one surface. The base 10 further includes a pedestal 12 in a region corresponding to the counterbore 11 on the other surface.

  Such a substrate 10 is particularly suitable for transferring a concavo-convex pattern by nanoimprint, and the substrate is particularly preferably made of quartz. If a template having a concavo-convex pattern is produced on the pedestal 12 provided on the surface of the base 10, the area where the template comes into contact with a transfer medium such as a wafer is used as the surface of the pedestal 12 when used in the device manufacturing process. Therefore, there is an advantage that contact with a structure existing outside the pattern formation region of the template can be avoided. The height (step) of the pedestal portion 12 is preferably 1-1000 μm, more preferably 10-500 μm, and still more preferably 20-100 μm.

  The substrate 10 is a 2-8 inch circular wafer or a rectangular size of 65 mm x 65 mm, 5 inches x 5 inches, 6 inches x 6 inches, or 9 inches x 9 inches, which is the size of a reticle used in semiconductor lithography. A substrate having a circular counterbore provided at the center of the back surface of the shaped substrate can be used. The shape of the counterbore part 11 is determined in consideration of the gas permeability and the degree of flexure (bending rigidity) of the substrate in the portion thinned by the counterbore processing.

  The configuration and effect of the thin film layer 20 of the substrate 2 with the thin film layer for pattern formation mask of the present embodiment are the same as the configuration and effect of the thin film layer 50 of the substrate 1 with the thin film layer for pattern formation mask of the first embodiment. It is.

A method of forming the thin film layers 20 and 50 on the substrates 10 and 40 in the substrates 1 and 2 with a thin film layer for pattern formation mask will be described.
The method for forming the thin film layers 20 and 50 is not particularly limited, but for example, vapor deposition, more specifically, sputtering, chemical vapor deposition, molecular beam epitaxy, or ion beam sputtering. Or the like. In particular, it is preferably formed by a sputtering method.

More specifically, the film formation by the sputtering method preferably uses Cr as a target and uses only a mixed gas of Ar gas and oxygen, or only Ar gas. When using O ₂ gas, the O ₂ gas flow rate ratio during sputtering is preferably 1/20 or less of Ar. DC (direct current) sputtering or RF (high frequency) sputtering can be used, and any of them may be used when sputtering is performed with Ar gas alone, and RF sputtering is performed when a mixed gas of O ₂ gas and Ar gas is used. It is preferable to use it.

  The amount of oxygen in the gas is appropriately determined in order to control the chromium content in the film obtained by sputtering. In order to control the oxygen content in the depth direction, oxygen may be introduced for a very short time at the start of film formation or during the film formation, if necessary.

  The thickness of the thin film layers 20 and 50 is 10 nm or less, and can be appropriately selected in consideration of the target processing depth of the concave and convex pattern recesses on the finally obtained substrate, the etching selectivity with the resist, and the transmittance. The lower limit of the thickness is about 0.5 nm required for uniformly forming a film on the substrate surface, but the thickness is 1 nm or more, more preferably 2.5 nm or more.

  As the mask pattern formed by etching the thin film layers 20 and 50 is narrower, the etching speed of the thin film layer at the bottom of the recesses is reduced due to the microloading effect. By setting the thickness of the thin film layer to 10 nm or less, the etching time at the time of mask pattern formation can be suppressed. As a result, the break (disconnection) defect caused by the disappearance of the resist pattern before the etching of the thin film layer is completed. Can be suppressed.

  In addition, by setting the chromium content of the thin film layer as a whole to 40 atomic% or more, the resistance of the mask when etching the substrate can be made sufficient, and the pattern shape of the convex section is close to a rectangle. Can be obtained. Further, by setting the chromium content to 50% atom or less, line edge roughness (LER) can be reduced, and the side wall angle can be made closer to 90 °. In addition, the standard which can be said that the processing precision of a mask pattern is high is that the side wall angle is 85 ° or more and the 3σ value of LER is 1/10 or less of the set line width.

  When an uneven pattern is to be accurately formed on the surfaces of the substrates 10 and 40, the mask pattern formed by etching the thin film layers 20 and 50 needs to have sufficiently high processing accuracy. By providing a thin film layer having a chromium content of 40 atom% or more and 50 atom% or less and 10 nm or less in the entire layer, a mask pattern with high processing accuracy can be obtained. As a result, 50 nm or less, 30 nm or less, An uneven pattern having a pattern line width of less than 30 nm can be formed on the processed surface of the substrate.

  Next, the manufacturing method of the patterned base | substrate of this invention is demonstrated. The manufacturing method of the patterned base | substrate of this invention is a method of manufacturing a patterned base | substrate from the base | substrate with the thin film layer for pattern formation masks mentioned above.

<Method for Producing Patterned Substrate of First Embodiment>
FIG. 3 is a diagram showing a process of the patterned substrate manufacturing method according to the first embodiment. Here, the process of producing the master template for nanoimprints as a patterned base | substrate using the base | substrate 1 with a thin film layer for pattern formation masks of 1st Embodiment is demonstrated.

  The patterned substrate manufacturing method of the present embodiment is prepared by preparing the substrate 1 with the thin film layer for pattern formation mask of the first embodiment (step a) and forming the mask layer 65 for patterning on the thin film layer 50. (Step bc), by performing an etching process using plasma of a mixed gas of oxygen and chlorine using the mask layer 65, the thin film layer 50 is patterned to form a mask pattern 55 (Step d). By using 55 as a mask, the surface of the substrate 40 is etched with a plasma containing fluorine to form an uneven pattern on the surface of the substrate 40 (step e), and the mask pattern 55 is removed to form a patterned substrate. 40A is obtained (step f).

  In step a of the present embodiment, for example, with a thin film layer for a pattern forming mask in which a thin film layer 50 is formed on a base 40 made of a quartz substrate having a 6 inch square and a thickness of 0.25 inch (0.635 cm). A substrate 1 is prepared.

  In the step bc for forming the mask layer 65, for example, a resist solution containing a PHS (polyhydroxystyrene) -based chemically amplified resist as a main component is applied by spin coating to form the resist layer 60, and thereafter An electron beam is irradiated while scanning the substrate 1 on an XY stage, and pattern exposure is performed on a 25 mm × 31 mm square area of the resist layer 60. Thereafter, the resist layer is developed, the exposed portion is removed, and a resist pattern (hereinafter referred to as resist pattern 65) is formed as a mask layer 65.

  In the step d of forming the mask pattern 55 by patterning the thin film layer 50, for example, reactive ion etching (RIE) is used as the etching. The RIE etching conditions are selected so that the etching selectivity of the thin film layer to the resist layer is increased. This is because when the selection ratio is reduced, the resist pattern partially disappears and a break (disconnection) defect occurs. Here, selection ratio is defined as: etching rate of thin film layer / etching rate of resist layer.

In this step d, in order to perform anisotropic etching, it is preferable to perform etching with bias power applied in an etching apparatus. By applying a bias power, etching proceeds anisotropically, and an increase in CD (Critical Dimension) can be suppressed. However, since the speed at which the resist pattern disappears increases if the bias power is too large, the bias input power is usually 0.01 W / inch ^{2 to} 0.3 W / inch ² (15.5 W / m ^{2 to} 465 W / m ^2. (The input power is indicated by a value ordered by the substrate area.). Details of the etching apparatus will be described later.

For the etching in this step d, a mixed gas of oxygen and chlorine is used, and etching using plasma of this mixed gas is performed. Since the thin film layer is made of chromium oxide, the chromium oxide can be etched by generating chromyl chloride (CrO ₂ Cl ₂ ) using a mixed gas of chlorine (Cl ₂ ) and oxygen (O ₂ ).

In the etching step e of the substrate 40 using the mask pattern 55 as a mask, it is preferable to use RIE as in the etching of the thin film layer, and it is particularly preferable to use ICP-RIE, CCP-RIE, or ECR-RIE. As an etching gas for the substrate 40 made of quartz, a mixed gas of a fluorine-based gas (CHF ₃ , CF ₄ , SF ₆ , and / or C ₄ F ₈ ) and a rare gas such as Ar, He, or Xe is used. The ratio of the fluorine-based gas to the rare gas is preferably 1 or less. Here, the ratio of the fluorine-based gas to the rare gas is a flow rate ratio (fluorine-based gas / rare gas) of the fluorine-based gas and the rare gas introduced into the etching apparatus.

  In the step f of removing the mask pattern 55, the mask pattern 55 can be removed by etching with a mixed gas of chlorine and oxygen, for example.

  Through the above steps, for example, it is possible to obtain a patterned substrate 40A in which a concavo-convex pattern composed of a groove-shaped line pattern having a width of 28 nm, a pitch of 56 nm, and a depth of 60 nm is formed at the center of the substrate 40 made of a quartz substrate. it can.

  This patterned substrate 40A can be used as a master template in the nanoimprint method. In addition, what the mold release process was performed by the dip coating method on the surface of this patterned base | substrate 40A can be used in the manufacturing method of the patterned base | substrate of the following 2nd Embodiment.

<Method for Producing Patterned Substrate of Second Embodiment>
FIG. 4 is a diagram illustrating a process of a method for manufacturing a patterned substrate according to the second embodiment. Here, the patterned substrate 40A manufactured by the method for manufacturing a patterned substrate of the first embodiment is used as a master template (hereinafter referred to as a master template) using the substrate 2 with a thin film layer for pattern formation mask of the second embodiment. A process for producing a sub-master template as a patterned substrate by transferring a concavo-convex pattern by a nanoimprint method will be described.

  In the method for producing a patterned substrate of this embodiment, the substrate 2 with a thin film layer for pattern formation mask of the second embodiment is prepared (step a), and a mask layer 35 for patterning is formed on the thin film layer 20. (Step b), by performing an etching process using plasma of a mixed gas of oxygen and chlorine using the mask layer 35, the thin film layer 20 is patterned to form a mask pattern 25 (step c), and the mask pattern 25 is masked. As a result, an uneven pattern is formed on the surface of the substrate 10 by performing an etching process using a plasma containing fluorine on the surface of the substrate 10 (step d), and the mask pattern 25 is removed to obtain a patterned substrate 10A ( Step e).

  In step a of the present embodiment, for example, the base 10 made of quartz having a size of 6 inches × 6 inches, a thickness of the portion that is not the counterbore portion 11 is 6.35 mm, a diameter of the circular counterbore portion is 63 mm, and a remaining thickness of the counterbore portion is 1.1 mm. In addition, a substrate 2 with a thin film layer for a pattern forming mask in which the thin film layer 20 is formed is prepared.

In the step b of forming the mask layer 35, a nanoimprint method using the master template 40A obtained by the patterned substrate manufacturing method of the first embodiment is used. FIG. 5 is a diagram schematically showing a process of forming a resist pattern (hereinafter referred to as resist pattern 35) as the mask layer 35 by the nanoimprint method. Formation of resist pattern 35 by nanoimprinting, the resist solution 30 step b ₁ of applying the _resist solution 30 of the master template 40A patterning mask thin film layer with the base body 2 on the thin film layer 20 formed on the base 10 The master template 40A is released from the resist pattern 35, the pressing step b ₂ that makes contact with the surface applied, the curing step b ₃ -b ₄ that hardens the concavo-convex pattern resist film 32, and the resist pattern 35. comprising a releasing step b ₅ in this order. Hereinafter, each step will be described.

[Resist solution application step b ₁ ]
First, the resist solution 30 to be used will be described.
The resist solution 30 is not particularly limited. For example, a material prepared by adding a photopolymerization initiator (about 2% by mass) and a fluorine monomer (0.1 to 1% by mass) to a polymerizable compound is used. Can be used. Moreover, antioxidant (about 1 mass%) can also be added as needed. The resist solution obtained by the above procedure can be cured by UV light having a wavelength of 360 nm. For those having poor solubility, a small amount of acetone or ethyl acetate is added and dissolved, and then the solvent is removed by distillation. Examples of the polymerizable compound include benzyl acrylate (Biscoat # 160: manufactured by Osaka Organic Chemical Co., Ltd.), ethyl carbitol acrylate (Biscoat # 190: manufactured by Osaka Organic Chemical Co., Ltd.), polypropylene glycol diacrylate (Aronix M-220: Tojo). Synthetic Co., Ltd.), trimethylolpropane PO-modified triacrylate (Aronix M-310: manufactured by Toagosei Co., Ltd.) and the like, Compound A represented by the following structural formula (1), and the like can be given. As the polymerization initiator, 2- (dimethylamino) -2-[(4-methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl] -1-butanone (IRGACURE 379: Toyotsu And alkylphenone photopolymerization initiators such as Chemiplus Co., Ltd.). Moreover, as said fluorine monomer, the compound B etc. which are represented by following Structural formula (2) can be mentioned. Here, the viscosity of the resist agent is preferably 8 to 20 cP, and the surface energy of the resist layer after application of the resist solution is preferably 25 to 35 mN / m.

  As a resist coating method for applying the resist solution, a method capable of disposing a predetermined amount of droplets at a predetermined position on the substrate or the master template, such as an ink jet method or a dispensing method, is used. However, a method capable of applying a resist with a uniform film thickness, such as a spin coating method or a dip coating method, may be used. When disposing the droplets on the substrate, an ink jet printer or a dispenser may be used depending on the desired droplet amount. For example, when the droplet amount is less than 100 nl (nanoliter), an ink jet printer is used, and when it is 100 nl or more, a dispenser is used.

  Examples of inkjet heads that eject droplets from nozzles include piezo methods, thermal methods, and electrostatic methods. Among these, a piezo method capable of adjusting an appropriate amount of liquid (amount per droplet disposed) and a discharge speed is preferable. Before arranging the droplets on the substrate, the droplet amount and the discharge speed are set and adjusted in advance. For example, the appropriate liquid amount is increased at a position on the substrate corresponding to a region where the spatial volume of the concave / convex pattern of the master template is large, and is decreased at a position on the substrate corresponding to a region where the spatial volume of the concave / convex pattern of the master template is small. It is preferable to adjust. Such adjustment is appropriately controlled according to the droplet discharge amount (the amount per discharged droplet). Specifically, when the droplet amount is set to 5 pl (picoliter), the droplet amount is controlled to be ejected five times to the same place using an inkjet head having a droplet ejection amount of 1 pl. . The amount of droplets can be obtained, for example, by measuring the three-dimensional shape of droplets discharged on the substrate in advance under the same conditions with a confocal microscope or the like and calculating the volume from the shape. After adjusting the droplet amount as described above, the droplets are arranged on the substrate according to a predetermined droplet arrangement pattern. The droplet arrangement pattern is constituted by two-dimensional coordinate information including a lattice point group corresponding to the droplet arrangement on the substrate.

  On the other hand, when using a spin coating method or a dip coating method, the resist is diluted with a solvent so as to have a predetermined thickness, and by controlling the number of rotations in the case of the spin coating method and the pulling speed in the case of the dip coating method. A uniform coating film may be formed on the substrate.

<Pressing step b ₂ >
Before bringing the master template 40A and the resist coating surface of the thin film layer 20 on the base 10 into contact with each other, the atmosphere between the master template 40A and the base 2 with the thin film layer for pattern formation mask is reduced to a vacuum or vacuum. Reduce residual gas. However, since the resist before curing is volatilized under a high vacuum atmosphere and it may be difficult to maintain a uniform film thickness, the atmosphere between the master template and the substrate is preferably a He atmosphere or a reduced pressure He atmosphere. To reduce residual gas. Since He permeates the quartz substrate, the trapped residual gas (He) gradually decreases. Since it takes time to permeate He, a reduced pressure He atmosphere is more preferable. The reduced pressure atmosphere is preferably 1 to 90 kPa, and particularly preferably 1 to 10 kPa.

  The master template 40A and the substrate 2 coated with the resist solution 30 are brought into contact with each other after being aligned so that they have a predetermined relative positional relationship. An alignment mark is preferably used for alignment.

  The pressing pressure of the master template 40A is performed in the range of 100 kPa to 10 MPa. When the pressure is higher, the flow of the resist solution is promoted, the compression of the residual gas, the dissolution of the residual gas into the resist, and the permeation of He into the quartz substrate are promoted, leading to an improvement in the removal rate of the residual gas. However, if the applied pressure is too strong, there is a possibility that the master template and the substrate with the thin film layer for the pattern forming mask may be damaged when foreign matter is caught when the master template comes into contact. Therefore, the pressing pressure of the master template is preferably 100 kPa or more and 10 MPa or less, more preferably 100 kPa or more and 5 MPa or less, and further preferably 100 kPa or more and 1 MPa or less. The reason for setting the pressure to 100 kPa or higher is that when the imprinting is performed in the atmosphere, when the space between the master template and the substrate with the thin film layer for pattern forming mask is filled with liquid, the master template and the substrate are at atmospheric pressure (about 101 kPa). This is because the pressure is applied.

<Curing step _b 3 _-b 4>
After the master template 40A is pressed to form the resist film 32, the resist pattern 32 is formed by exposing with light containing a wavelength matched to the polymerization initiator contained in the resist solution and curing the resist.

<Releasing step _b 5>
The master template 40A is peeled off (released) from the resist pattern 35 after curing. As a mold release method, one of the back surface or outer edge portion of the master template 40A or the substrate 10 is held, and the other back surface or outer edge portion is held, and the holding portion of the outer edge or the holding portion of the back surface is opposite to the pressing direction. A relative movement method can be mentioned.

After releasing the master template 40A as described above, residual film etching is performed to remove the residual resist film formed on the bottom of the concave portion of the resist pattern 35, and subsequently, steps c and d in FIG. The patterned substrate 10A is obtained through this etching process.
Each of these etching processes will be described. FIG. 6 is a schematic view showing an example of an etching apparatus 100 for performing each etching process.

  The etching apparatus 100 includes a processing container (chamber) 101 capable of maintaining an atmosphere reduced in pressure from atmospheric pressure, a pressure adjusting unit 102a for reducing the pressure inside the processing container 101 to a predetermined pressure, and an exhaust system such as a vacuum pump. A decompression unit 103 including 102b, a substrate mounting structure unit 110 which is provided inside the processing vessel 101 and on which a substrate to be processed is mounted and which supports and fixes the substrate to be processed, and a high-frequency power source 105 for generating plasma. And a plasma generation unit 107 including a plasma generation antenna 106.

  The substrate mounting structure section 110 includes a lower electrode 112, and the apparatus 100 includes a bias power source 108 for applying a bias voltage connected to the lower electrode 112 via a matching box 118. . Further, a temperature regulator 104 that controls the temperature of the substrate mounting structure 110 and a gas introduction unit 109 that includes a gas flow rate controller for introducing a desired gas into the processing container 101 are provided.

  The etching performed in the apparatus 100 is preferably RIE. In particular, as a mechanism for generating plasma, inductively coupled plasma (ICP) -RIE, capacitively coupled plasma (CCP) -RIE, or electron cyclotron resonance type is used. (ECR) -RIE is preferred. In this embodiment, in order to facilitate control of bias power (power for forming a bias between the plasma and the lower electrode), control is possible independently of plasma power (power for forming plasma). Is adopted.

(1) Residual Film Etching Residual film etching is for removing the resist residual film formed on the bottom of the pattern recess when the resist pattern 35 is formed by the nanoimprint method shown in steps b _{1 to} b ₄ of FIG. It is this process. As the etching gas, oxygen gas, argon gas, or fluorocarbon gas can be used.

(2) Etching of thin film layer (step c in FIG. 4)
The etching process of the thin film layer 20 can be performed in the same manner as the etching process of the thin film layer 50 in the patterned substrate manufacturing method of the first embodiment.

(3) Etching of substrate (step d in FIG. 4)
The process of etching the substrate 10 using the mask pattern 25 obtained by patterning the thin film layer 20 as a mask can be performed in the same manner as the etching process in the patterned substrate manufacturing method of the first embodiment.

Through the above etching process, a concavo-convex pattern corresponding to the resist pattern 35 is formed on the surface of the base 10, and the concavo-convex patterned base 10 </ b> A can be obtained.
In the method of manufacturing the patterned substrate 10A of the present embodiment, the patterned substrate 40A of the first embodiment is used as a master template for forming a resist pattern by the imprint method. A prepared one or one prepared by another method may be used.

  Examples of the present invention and comparative examples will be described below.

<Preparation of substrate with thin film layer for pattern formation mask>
As a substrate of a substrate with a thin film layer for a pattern forming mask, a quartz substrate of 152 mm square and a thickness of 6.35 mm has a pedestal shape of 26 mm × 32 mm square and a height of 30 μm as a transfer area at the center of the quartz substrate. What was formed by wet etching and used a counterbore having a diameter of 63 mm and a depth of 5 mm provided at the center of the back surface of the substrate.

A thin film layer for a pattern forming mask was formed on the substrate by sputtering to form chromium oxide by RF sputtering. At this time, the RF sputtering conditions are a base vacuum degree of 8.0 × 10 ⁻⁴ Pa or less, an RF power of 150 W, a vacuum degree during deposition, a ratio of gas types, and a film thickness (target film thickness). As shown in Table 1 below, the substrates with a thin film layer for pattern formation masks of Examples 1-4 and Comparative Examples 1-13 were prepared.

The composition of the thin film layer of each example and comparative example was measured by obtaining the depth profile of the contained element by X-ray photoelectron spectroscopy while performing Ar etching in a region that does not become a concavo-convex pattern forming region in the subsequent process. . An example of a profile is shown in FIG. In FIG. 7, the horizontal axis represents the sputtering time. t _f corresponds to the boundary position between the chromium oxide thin film layer and the quartz substrate.
For each element, the depth dependency of the element content is measured, and the ratio of the value obtained by integrating the element content in the depth direction is defined as the content (atomic%) of each element in the film. The content (atomic%) was determined.

<Preparation of Patterned Substrates from Substrates with Thin Film Layers for Pattern Formation Masks of Examples and Comparative Examples>
Surface treatment with KBM-5103 (manufactured by Shin-Etsu Chemical Co., Ltd.), which is a silane coupling agent having excellent adhesion to the resist, on the surface of the thin film layer of the substrate with the thin film layer for pattern forming mask of each Example and Comparative Example Was given. Specifically, KBM-5103 is diluted to 1% by mass with PGMEA (propylene glycol 1-monomethyl ether 2-acetate), and applied to the surface of the thin film layer of the substrate with the thin film layer for pattern formation mask by spin coating. Then, the substrate with a thin film layer for pattern forming mask to which the diluted solution was applied was annealed on a hot plate at 150 ° C. for 5 minutes to bond the silane coupling agent to the substrate surface.

(Resist pattern formation process)
Here, resist pattern formation was performed by the nanoimprint method.
A master template in which a groove-shaped line pattern having a width of 28 nm, a pitch of 56 nm, and a depth of 60 nm was formed in a 25 mm × 31 mm square range at the center on a 6-inch square and 0.25-inch thick quartz substrate was used. . The taper angle of the groove of the master template was 86 °. The surface of the master template was subjected to mold release treatment using OPTOOL (registered trademark) DSX by a dip coating method.

  48 w% of the compound A represented by the chemical formula (1) described above, 48 w% of the Aronix (registered trademark) M220, 3 w% of IRGACURE (registered trademark) 379, and the compound B represented by the chemical formula (2) described above. Was prepared, and this resist agent was applied on the thin film layer of the substrate with a thin film layer for pattern forming masks of Examples and Comparative Examples. For the application of the resist agent, DMP-2838 manufactured by FUJIFILM Dimatix, which is a piezo ink jet printer, was used. DMC-11610, a dedicated 10 pl (picoliter) head, was used as the inkjet head. The droplet arrangement pattern was a grid pattern with a pitch of 450 μm. The ejection conditions were set and adjusted in advance, and droplets were placed in the transfer region (on the substrate base) according to this droplet placement pattern.

The master template and the substrate with the thin film layer for pattern formation mask are brought close to the position where the gap is 0.1 mm or less, and the alignment mark on the substrate and the alignment mark on the master template are aligned from the back of the substrate. I do. The space between the master template and the substrate with the thin film layer for pattern formation mask was replaced with 99% by volume or more of He gas, and the pressure was reduced to 50 kPa or less after the He replacement. The master template was brought into contact with droplets made of resist under reduced pressure He conditions. After contact, pressurize for 5 seconds with a pressing pressure of 1 MPa, and then expose the UV light containing a wavelength of 360 nm to an irradiation dose of 300 mJ / cm ² to cure the resist, and then pattern formation with the master template The substrate with the thin film layer for mask was peeled off.

  After the resist pattern was formed by the nanoimprint method, the following etching and ashing were sequentially performed. In either case, an inductively coupled (ICP) reactive ion etching apparatus was used.

<Residual film etching>
First, after the resist pattern was formed by the nanoimprint method, residual film etching was performed under the following etching conditions in order to remove the resist film remaining in the recesses.
Gas type; oxygen: argon = 2: 1
Process pressure: 1 Pa
ICP power: 100W
Bias power: 50W
Over etching amount: 50%

<Etching of thin film layer>
Next, using the resist pattern as a mask, the thin film layer was etched under the following etching conditions to form a mask pattern.
Gas type; Chlorine: Oxygen = 4: 1
Process pressure: 4.5Pa
ICP power; 300W
Bias power: 5W
Over etching amount: 100%

<Substrate (quartz) etching>
Next, the substrate (quartz) was etched under the following etching conditions using the mask pattern of the thin film layer as a mask.
Gas type; CHF ₃ : SF ₆ : Ar = 10: 1: 50
Process pressure: 3Pa
ICP power; 75W
Bias power; 75W
Target depth: 60nm

<Mask removal>
Further, the mask was removed under the following conditions.
Gas type; Chlorine: Oxygen = 3: 1
Process pressure: 5Pa
ICP power: 100W
Bias power 0W

  Through the above etching process, a concavo-convex pattern was formed on the substrate surface of the substrate with a thin film layer for a pattern forming mask of each Example and Comparative Example to produce a patterned substrate.

(Evaluation)
About the patterned base | substrate produced from the base | substrate with a thin film layer for pattern formation masks of each Example and a comparative example, the surface uneven | corrugated pattern was observed with the electron microscope, and the following evaluation was performed.
The top surface (TOP-VIEW) and the cross section were observed, and the 3σ of LER and the side wall angle were obtained from image analysis.
Here, with respect to the σ value of LER, 500 points of edge points (boundary points) of line patterns at arbitrary positions are extracted from the TOP-VIEW electron microscope image observed at a magnification of 100,000 at 1 nm intervals along the edges. Then, the σ value of LER was calculated from the coordinate information of these edge points. This was performed for any 10 locations in the line pattern, and the average value was adopted as the final σ value to determine 3σ of LER.
The side wall angle is the side wall rising angle of the convex pattern, and the pattern irregular boundary line in the cross section is extracted from the cross-sectional image of the electron microscope observed at 150,000 times, and between the top of the pattern convex part and the bottom of the pattern concave part The inclination angle of the pattern edge boundary line at the position at the height of was determined. This was calculated | required about arbitrary 10 places, and made the average value the final side wall angle.

  When LER (3σ value) ≦ 2.8 nm and the side wall angle was 85 ° or more, it was evaluated as good (G), and other cases were evaluated as defective (N). Moreover, all that could not be measured due to pattern formation failure were evaluated as defective (N).

Table 1 summarizes the film forming conditions of the thin film layer, the Cr content in the thin film layer, the LER of the patterned substrate, and the sidewall angle. Although the thin film layer is described as a target film thickness, it was confirmed that the actual film thickness was within ± 5% of the target film thickness.

  In Comparative Examples 8 to 9, in the mask pattern of the thin film layer, the thin film layer in the region to be the space portion (recessed portion) was not etched enough, so that the uneven pattern could be formed on the surface of the substrate. There wasn't. In Comparative Examples 10 to 13, since the etching resistance of the mask pattern of the thin film layer was weak, pattern formation of the concavo-convex pattern on the substrate surface was poor.

  FIG. 8 is a diagram in which examples and comparative examples are plotted with the thickness of the thin film layer as the vertical axis and the chromium content in the thin film layer as the horizontal axis. In FIG. 8, an example is indicated by a white circle (◯), and a comparative example is indicated by a black circle (●). FIG. 8 also shows scanning electron microscope images of the top surface and the cross section of the concavo-convex pattern on the surface of the patterned substrate for Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 10. In Example 1, it can be confirmed that the LER is suppressed and a concave-convex pattern having a favorable side wall angle is formed. On the other hand, in Comparative Examples 1, 2, and 10, it is confirmed that the side wall angle is dull, and in Comparative Example 10, the height of the convex portion is very low and the LER is also large.

  As shown in FIG. 8, the LER and sidewall angle after quartz dry etching are excellent in a region surrounded by a broken line and having a chromium content of 40 to 50 atomic% and a thickness of 10 nm or less as a whole film. Further, since the resistance as an etching mask can be secured, the effectiveness of the present invention was shown.

DESCRIPTION OF SYMBOLS 1, 2 Base | substrate with thin film layer for pattern formation masks 10, 40 Base | substrate 10A, 40A Patterned base | substrate 11 Counterbore part 12 Base part 20, 50 Thin film layer 25, 55 Mask pattern 30 Resist liquid 32 Resist film 35 Mask layer (resist pattern)

Claims (8)

A substrate made of silicon or a silicon-based compound;
It is patterned by an etching process using plasma of a mixed gas of oxygen and chlorine provided on the surface of the substrate, and comprises a thin film layer used as a mask for pattern formation,
A substrate with a thin film layer for a pattern forming mask, wherein the thin film layer is made of a chromium oxide having a chromium content of 40 atomic% or more and 50 atomic% or less. A substrate made of silicon or a silicon-based compound, and a thin film layer having a thickness of 10 nm or less made of chromium oxide having a chromium content of 40 atom% or more and 50 atom% or less provided on the surface of the substrate. Prepared a substrate with a thin film layer for a pattern forming mask,
Forming a patterning mask layer on the thin film layer;
Using the mask layer, the thin film layer is patterned by performing an etching process using plasma of a mixed gas of oxygen and chlorine,
A method of manufacturing a patterned substrate, wherein the surface of the substrate is patterned by performing an etching process using plasma containing a fluorine-based gas using the patterned thin film layer as a mask.   The manufacturing method of the patterned base | substrate of Claim 2 including a part below 50 nm as a pattern line | wire width in the said patterning.   The method for producing a patterned substrate according to claim 2 or 3, wherein a ratio of oxygen to chlorine in the mixed gas of oxygen and chlorine is 0.05 to 0.40.   The method for producing a patterned substrate according to any one of claims 2 to 4, wherein the fluorine-containing gas content in the plasma containing the fluorine-containing gas is 50% or less.   6. The patterning mask layer according to claim 2, wherein the patterning mask layer is formed by applying a resist film on the thin film layer and forming an uneven pattern on the resist film by an imprint method. Production method.   The method for producing a patterned substrate according to claim 2, wherein the patterned substrate is a nanoimprint template.   The method for producing a patterned substrate according to any one of claims 2 to 6, wherein the patterned substrate is an optical element.

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