WO2011040477A1

WO2011040477A1 - Method for manufacturing mold for imprint, mold with unremoved remaining hard mask layer, method for manufacturing mold with unremoved remaining hard mask layer, and mask blank

Info

Publication number: WO2011040477A1
Application number: PCT/JP2010/066966
Authority: WO
Inventors: 光浩暮石; 秀司岸本
Original assignee: Hoya株式会社
Priority date: 2009-09-30
Filing date: 2010-09-29
Publication date: 2011-04-07
Also published as: JP2011096686A

Abstract

Disclosed is a method for manufacturing a mold for imprint, wherein, in a step of forming, on a substrate, a hard mask layer including a conductive layer composed of a material containing a compound having Ta as a main component or at least an element, i.e., Hf or Zr, or a compound of such elements, and removing the hard mask layer from the mask blank having a resist layer for pattern formation formed thereon, the hard mask layer is removed by dry-etching with a reductive gas introduced.

Description

Imprint mold manufacturing method, residual hard mask layer removal mold and manufacturing method thereof, and mask blanks

The present invention relates to a method for manufacturing an imprint mold, a mold before removing a remaining hard mask layer, a method for manufacturing the same, and a mask blank, and in particular, a mold before removing a remaining hard mask layer in which a hard mask layer having a fine pattern is applied on a substrate. The present invention relates to a method for producing an imprint mold from the above, a mold before removing the remaining hard mask layer used in the method, a method for producing the mold, and a mask blank as a basis thereof.

Conventionally, in a magnetic disk used in a hard disk or the like, a method has been used in which the magnetic head width is minimized and the data tracks on which information is recorded are narrowed to increase the density. On the other hand, the density of this magnetic disk has been increased and the magnetic influence between adjacent tracks cannot be ignored. For this reason, the conventional method has a limit in increasing the density.

Recently, a new type of media called Discrete Track Recording Media (hereinafter referred to as DTR media) in which data tracks of a magnetic disk are magnetically separated has been proposed.

The DTR media is intended to improve signal quality by removing (grooving) a portion of magnetic material that is not necessary for recording. Specifically, after the grooves are processed, the grooves are filled with a non-magnetic material to realize angstrom level surface flatness required for a magnetic disk drive. An imprint technique is used as one of the techniques for performing this fine width groove processing. A new type of media called bit-patterned media (medium for recording signals as bit patterns (dot patterns)), which has been developed by further increasing the density of this DTR media, has been proposed. Imprint technology is also considered promising in pattern formation.
Hereinafter, for convenience of description of the present invention, the case of DTR media (that is, the case of a line and space pattern) will be mainly described in this specification. However, “grooving” in the present specification includes a case where a hole portion corresponding to the bit pattern or a portion other than the cylindrical portion corresponding to the bit pattern is removed from the bit patterned medium.

There are two main types of imprint technology, thermal imprint and optical imprint. Thermal imprinting is a method in which a mold on which a fine pattern is formed is pressed against a thermoplastic resin as a molding material while being heated, and then the molding material is cooled and released to transfer the fine pattern. Optical imprinting is a method in which a mold on which a fine pattern is formed is pressed against a photocurable resin that is a molding material, irradiated with ultraviolet light, and then the molding material is released to transfer the fine pattern. is there.

In the production of the optical imprint mold mentioned here, mask blanks in which a film containing chromium or the like is formed on a light-transmitting substrate such as quartz glass are used. After applying a resist on the mask blanks, a resist pattern is formed using electron beam exposure or the like. Then, the fine pattern is formed by etching the film using the resist pattern as a mask. Thereafter, the groove processing as described above is performed on the translucent substrate using the fine pattern in the film as a mask.

However, when the groove processing is performed using oxygen gas and chlorine gas at the time of etching the film as described above, the following problems may occur.

For example, when performing etching, if the convex part other than the groove has a narrow width of 100 nm or less and a thick width of 1 μm or more at the same time, the micro-width part becomes relatively narrow due to the etching. A loading effect will occur.

Also, when oxygen gas and chlorine gas are used, etching proceeds not only in the resist thickness direction but also in the lateral direction of the resist cross section. Therefore, the width of the resist changes during dry etching of the chromium film, and as a result, the width of the chromium pattern also changes with respect to the resist width before etching. In addition, since the chrome pattern itself is gradually etched in the cross-sectional lateral direction, the width of the chrome pattern becomes thinner than a desired dimension, and the narrow pattern itself may disappear.

Further, when the pattern size is miniaturized, the resist film thickness is restricted in addition to the problem of the etching bias of the chromium film. When the resist film thickness is approximately three times the pattern width or more, the resist exposure time is reduced. There is also a possibility that problems such as degradation of resolution and pattern collapse after resist pattern formation may occur.

In order to solve the above problems, a hard mask layer having a conductive layer (TaHf layer) as a lower layer and an antioxidant layer (CrO layer) for a conductive layer as an upper layer is provided on a translucent substrate, and oxygen is substantially added. A technique of performing dry etching using a gas that does not include is disclosed by the present applicant (see Patent Document 1). Further, by the same applicant, the technology in which oxygen is not used in the CrN film forming process by changing the chromium oxide layer (CrO layer) on the hard mask layer in Patent Document 1 to a chromium nitride layer (CrN layer). It is disclosed (see Patent Document 2).

JP 2009-80421 A JP 2009-98689 A

As described above, in the techniques disclosed in

Patent Documents

1 and 2, a hard mask layer (a conductive layer and an antioxidant layer) having a fine pattern is provided on a translucent substrate, and grooves corresponding to the pattern are formed in the translucent substrate. A mold before removal of the remaining hard mask layer provided on the conductive substrate is disclosed. Then, the hard mask layer in the mold before removal of the remaining hard mask layer is removed to produce an imprint mold.

Certainly, in

Patent Documents

1 and 2, dry etching is performed in an atmosphere substantially free of oxygen to solve the above-described problems. However, oxygen may still remain in the etching apparatus or may be generated during the process. This residual oxygen may suppress the progress of dry etching.

Sources of this residual oxygen include oxygen remaining in the etching apparatus, oxygen generated from members constituting the etching apparatus, oxygen generated from the substrate by dry etching when quartz is used for the substrate, and the like. Can be mentioned.

In particular, with respect to oxygen remaining in the etching apparatus before pattern formation, when the hard mask layer is etched so as to correspond to the pattern shape, the conductive layer is protected with a CrN layer or the like, During the dry etching for pattern formation, the lower conductive layer may be oxidized.

As a result, residual oxygen present in the etching apparatus may affect dry etching when removing the hard mask layer. That is, the TaHf layer that should have been prevented from being oxidized by the bent CrN layer or the like is oxidized by this residual oxygen during etching, and an oxide film is formed on the surface thereof. And there exists a possibility that progress of an etching may be suppressed by this oxide film.

At this time, even if the progress of chemical etching is suppressed by the oxide film, physical etching may be performed by increasing the output of the etching apparatus. However, by doing this, it becomes difficult to set a desired etching selectivity between the hard mask layer and the substrate this time, which may lead to roughness of the substrate surface, dimensional change of the fine pattern, and the like. Furthermore, when quartz is used for the substrate, oxygen is generated from the substrate by physical etching, which may cause an oxide film to be formed on the surface of the TaHf layer.

The object of the present invention has been made in consideration of the above-described circumstances, and is capable of smoothly performing dry etching on a hard mask layer and manufacturing an imprint mold that forms a fine pattern with high pattern accuracy. It is to provide a method, a mold before removing a residual hard mask layer, a method for manufacturing the mold, and mask blanks.

In a first aspect of the present invention, a hard mask layer including a conductive layer made of a compound containing Ta as a main component or at least one element of Hf and Zr or a material containing the compound is formed on a substrate, In the step of removing the hard mask layer from the mask blank in which the resist layer for pattern formation is formed on the mask layer, the hard mask layer is removed by dry etching into which a reducing gas is introduced.
According to a second aspect of the present invention, in the invention according to the first aspect, the substrate is a translucent quartz substrate, the conductive layer is made of Ta and Hf, and the reducing gas contains BCl _3. It is characterized by.
In a third aspect of the present invention, a hard mask layer having a conductive layer made of a compound containing Ta as a main component, at least one element of Hf and Zr, or a material containing the compound is formed on a substrate, A step of forming a resist layer for pattern formation on the mask layer, and developing the resist layer on which a pattern for forming a groove is drawn on the substrate, and then reducing the resist layer and the hard mask layer in the groove forming portion. Step of removing by first dry etching in which gas is introduced, and second dry etching is performed on the light-transmitting substrate in the portion of the removed conductive layer, and then the resist layer in a portion other than the groove forming portion And a remaining hard mask layer removing step of removing a conductive layer in a portion other than the groove forming portion by a third dry etching in which a reducing gas is introduced. And wherein the Rukoto.
According to a fourth aspect of the present invention, in the invention according to the third aspect, the substrate is a translucent quartz substrate, the conductive layer is made of Ta and Hf, and the first and third dry etchings are performed. , Using a reducing gas containing BCl ₃ and a chlorine gas, and in the second dry etching, a fluorine-based gas or a gas obtained by adding a rare gas to a fluorine-based gas is used.
According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, an antioxidant layer made of chromium nitride is provided on the conductive layer.
According to a sixth aspect of the present invention, a conductive layer made of a compound containing Ta as a main component, at least one element of Hf and Zr, or a material containing the compound is provided on the substrate, and the conductive layer is provided on the conductive layer. Forming a hard mask layer having an antioxidant layer for a conductive layer, forming a resist layer for pattern formation on the hard mask layer, and drawing the pattern for forming a groove on the substrate After developing the resist layer, the step of removing the resist layer and the hard mask layer in the groove forming portion by the first dry etching into which the reducing gas is introduced, and the step of forming the groove in the substrate And a step of removing the resist layer in a portion other than the groove forming portion after performing the dry etching of step 2, and a method of manufacturing a mold before removing the remaining hard mask layer A.
According to a seventh aspect of the present invention, there is provided a conductive material comprising at least part of a substrate having a pattern formed by grooves, a compound containing Ta as a main component, at least one element of Hf and Zr, or a material containing the compound. A mold before removal of the remaining hard mask layer, wherein a hard mask layer having a layer and not having an antioxidant layer for the conductive layer is formed.
According to an eighth aspect of the present invention, the substrate has a conductive layer made of a compound containing Ta as a main component, at least one element of Hf and Zr, or a material containing the compound, and the antioxidant for the conductive layer is provided. A mask blank is characterized in that a hard mask layer having no layer is formed, and a resist for pattern formation is formed on the hard mask layer.

According to the present invention, the progress of dry etching on the hard mask layer can be performed smoothly, and a fine pattern can be formed with high pattern accuracy.

It is a section schematic diagram for explaining a manufacturing process of an imprint mold concerning this embodiment. It is a cross-sectional schematic diagram for demonstrating the manufacturing process of the mold for imprint which has a base structure which concerns on another embodiment. It is a cross-sectional schematic diagram for demonstrating the manufacturing process of the mold for imprint which concerns on another embodiment. It is a figure which shows the result observed using the scanning electron microscope about the imprint mold obtained by Example 1 and the comparative example, (a) is Example 1 and (b) is for imprint in a comparative example. It is a photograph which shows the surface of a mold.

The present inventors have studied various means for suppressing oxidation of the hard mask layer due to residual oxygen in the etching apparatus, more precisely, oxidation of the conductive layer in the hard mask layer.
As a result, the present inventors have found that the reducing gas, which is not so easy to handle in the process of removing the hard mask layer from the mask blanks until the imprint mold is manufactured, should be expensive. I thought of performing dry etching while using this. As a result, it has been found that the residual oxygen can be greatly reduced from the stage before the pattern is formed on the hard mask layer, and the risk of surface oxidation of the conductive layer can be reduced in the subsequent process. Furthermore, in dry etching using this reducing gas, even if the surface of the conductive layer is oxidized by residual oxygen, the oxidized surface can be reduced. By adding the reducing gas, etching proceeds while reducing the surface oxide layer. Found to do

<Embodiment 1>
Hereinafter, based on the knowledge of the present invention, the best mode for carrying out the present invention will be described based on FIG. 1, which is a diagram showing a method for manufacturing an imprint mold 20 according to the present embodiment.

First, as shown in FIG. 1A, a substrate 1 for an imprint mold 20 is prepared.
The substrate 1 may be a conventional substrate as long as it can be used as the imprint mold 20. However, in the case of performing optical imprinting, the substrate 1 is preferably a transmissive substrate from the viewpoint of light irradiation to a transfer material. . Examples of the transmissive substrate 1 include a glass substrate such as a quartz substrate. In the case of performing thermal imprinting, an SiC substrate that is resistant to chlorine gas used for dry etching on a hard mask layer to be described later can be used.

In addition, about the board | substrate 1 in the case of performing a thermal imprint, although the SiC substrate which is a board | substrate which has tolerance with respect to chlorine type gas was mentioned, the tolerance to chlorine type gas is comparatively given by giving the following devices. Weak silicon wafers can also be used. That is, instead of providing the conductive layer 2 on the silicon wafer 1, an SiO ₂ layer is provided. Conductive layer 2 on top of the SiO ₂ layer, by providing the anti-oxidation layer 3 protected, even as a conductive layer 2 and the oxide prevention layer 3 has been removed by chlorine gas, the SiO ₂ layer is a silicon wafer 1 from a chlorine gas Will do. Then, the SiO ₂ layer is removed with buffered hydrofluoric acid (hereinafter also referred to as BHF), that is, a mixed acid composed of ammonium fluoride and hydrofluoric acid. By doing so, a silicon wafer can also be used to produce a thermal imprint mold. Further, those having a SiO ₂ layer as a working layer on the silicon wafer can be used as a substrate. At this time, since a groove is provided in the SiO ₂ layer which is a processed layer, it is preferable to make the SiO ₂ layer thicker than when the silicon wafer 1 is used.

Further, as for the shape of the substrate 1, it is preferably a disc shape. This is because the resist can be applied uniformly while rotating the disk substrate 1 when applying the resist. The shape may be other than a disk shape, and may be a rectangle, a polygon, or a semicircle.
In the present embodiment, description will be made using a disk-shaped quartz substrate 1.

Next, as shown in FIG. 1B, the quartz substrate 1 is introduced into a sputtering apparatus. In this embodiment, a target made of an alloy of tantalum (Ta) and hafnium (Hf) is sputtered with argon gas to form a conductive layer 2 made of a tantalum-hafnium alloy, and a groove formed on the substrate 1 It is preferable to use the lower layer (conductive layer 2) of the hard mask layer 7 having a fine pattern corresponding to. The tantalum-hafnium alloy is preferable because it is a material that can be etched by a dry etching process using a chlorine-based gas, and the conductivity required to prevent charge-up when drawing an electron beam during mask manufacturing. Can be provided, and thereby the contrast at the time of alignment can be increased.

As a material for the conductive layer 2, in the case of a compound containing Ta as a main component, Ta compounds such as TaHf, TaZr, TaHfZr, and alloys thereof are suitable. On the other hand, at least one element of hafnium (Hf) and zirconium (Zr) or a compound thereof (for example, HfZr) can be selected, and these materials are used as base materials, for example, B, Ge, Nb, Si, C, and the like. , N and other sub-materials can be selected. In the present embodiment, the conductive layer 2 made of a tantalum-hafnium (TaHf) alloy will be described.

Next, in the present embodiment, from the viewpoint of preventing oxidation, the conductive layer 2 is not exposed to the atmosphere, and a chromium target is sputtered with a mixed gas of argon and nitrogen to form a chromium nitride layer 3. The upper layer (antioxidant layer 3 for conductive layer) in the hard mask layer 7 having a pattern is preferably used. The reason is as follows.

By forming the chromium nitride layer 3 on the upper surface of the conductive layer 2, oxidation of the lower conductive layer 2 can be prevented. Specifically, the surface of the chromium nitride layer 3 is mainly oxidized in place of the conductive layer 2 made of a tantalum-hafnium alloy when exposed to the air after the hard mask layer 7 is formed and in the baking process in the resist coating process. Is done. When dry etching is performed with a chlorine-based gas in a state where the surface of the chromium nitride layer 3 is oxidized, a much higher etching rate can be obtained than when the surface of the conductive layer 2 is oxidized. Moreover, in the process of producing the imprint mold 20 from the mold 10 before removing the remaining mask layer, even if cleaning is performed using ammonia water or perhydrosulfuric acid used for removing the resist layer 4, chromium nitride is used. Layer 3 is sufficiently resistant. Further, when the oxidation preventing layer 3 is made of chromium nitride, it is not necessary to use oxygen gas when sputtering the chromium nitride layer, and this also has a positive effect from the viewpoint of reducing residual oxygen.

The material of the antioxidant layer 3 is preferably chromium nitride (CrN) from the viewpoint that it is not necessary to use oxygen in sputtering during film formation, but any other compound that can be used as the antioxidant layer may be used. . For example, a molybdenum compound, chromium oxide (CrO), SiC, amorphous carbon, or Al may be used. In the present embodiment, the antioxidant layer 3 made of chromium nitride (CrN) will be described.

Thus, as shown in FIG. 1B, a hard mask layer 7 with the tantalum-hafnium alloy layer 2 as the lower layer and the chromium nitride layer 3 as the upper layer is formed on the quartz substrate 1. The “hard mask layer” in the present embodiment is composed of a single layer or a plurality of layers, and can protect a portion where a groove corresponding to a pattern is formed, and is a layered layer used for etching a groove. Shall point to.

Next, as shown in FIG. 1C, an electron beam drawing resist is applied to the hard mask layer 7 to form a resist layer 4, which is used for manufacturing an imprint mold in this embodiment. Mask blanks to be manufactured. As a resist for electron beam drawing, any resist suitable for the subsequent etching process may be used.

If the resist layer 4 is a positive resist, the electron beam drawn position corresponds to the position of the groove on the substrate 1, and if the resist layer is a negative resist, the opposite position is obtained. In the present embodiment, a case where a positive resist is used, that is, a case where a portion drawn on the resist layer 4 corresponds to the position of a groove in the substrate 1 will be described.

In addition, the thickness of the resist layer 4 at this time is preferably a thickness that remains until the etching of the hard mask layer 7 is completed. This is because not only the hard mask layer 7 but also the resist layer 4 in this portion are removed when the hard mask layer 7, that is, the conductive layer 2 and the antioxidant layer 3 in the drawing pattern portion is removed.

Next, a fine pattern is drawn on the resist layer 4 of the mask blank using an electron beam drawing machine. This fine pattern may be on the micron order, but may be on the nano order from the viewpoint of the performance of electronic devices in recent years, and this is preferable in view of the performance of the final product.

1) After the fine pattern drawing, as shown in FIG. 1D, the resist layer 4 is developed, the electron beam drawn portion of the resist is removed, and a resist pattern corresponding to a desired fine pattern is formed. The position of the drawn fine pattern corresponds to the position of the groove to be finally processed on the substrate 1.

(First dry etching)
Next, the substrate 1 having a resist pattern formed on the substrate is introduced into a dry etching apparatus. Normally, the first dry etching with chlorine gas containing substantially no oxygen is performed to remove the conductive layer 2 and the antioxidant layer 3 in the portion where the resist layer 4 has been removed.

However, as described above, the remaining oxygen in the etching apparatus not only oxidizes the surface of the antioxidant layer 3 (CrN layer) before the first dry etching, but also the conductive layer 2 (TaHf layer). Even the oxidation may occur.
Further, even during dry etching, there is a possibility that the conductive layer 2 that should have been protected by the antioxidant layer 3 may be oxidized by removing the antioxidant layer 3 by etching. As a result, an oxide film is formed on the surface of the conductive layer 2 and the progress of etching may be hindered.

Therefore, in the step of removing the hard mask layer in the present embodiment, the hard mask layer in a portion other than the groove forming portion is removed by performing the first dry etching while introducing the reducing gas. Hereinafter, the first dry etching will be described in detail.

First, the substrate 1 having a resist pattern formed on the substrate is introduced into a dry etching apparatus. In this embodiment, the first dry etching is performed in a reducing gas atmosphere that does not substantially contain oxygen. At this time, a chlorine-based gas may be used as a gas for removing the hard mask layer 7 in the first dry etching, or another halide-based gas suitable for removing the hard mask layer may be used. Examples of the chlorine-based gas used here include Cl ₂ , BCl ₃ , HCl, a mixed gas thereof, or a gas containing a rare gas (such as He, Ar, or Xe) as an additive gas. Further, by using a chlorine gas that does not contain oxygen in this dry etching, unnecessary oxidation of TaHf that is the conductive layer 2 can be suppressed. By doing so, the whole hard mask layer 7 can be etched smoothly.
In this embodiment, the case where chlorine gas is introduced together with the reducing gas will be described.

At this time, as the reducing gas, any reducing gas may be used, and examples thereof include a chlorine-based gas, a hydrogen gas, and a hydrocarbon-based gas that do not contain oxygen and include a reducing gas. A gas containing boron trichloride (BCl ₃ ) is preferable. The presumed chemical reaction mechanism including the reason will be described.

First, before starting the first dry etching, chlorine gas and BCl ₃ gas are introduced into an etching apparatus in which a slight residual oxygen exists. At this time, both gases may be supplied at the same time, but after etching to such an extent that the chromium nitride layer 3 is removed, a BCl ₃ gas may be introduced with a time difference. By doing so, the chromium nitride layer 3 is etched using only chlorine gas. As a result, the etching can proceed extremely stably until at least the removal of the chromium nitride layer 3.

After the chromium nitride layer 3 is removed by dry etching in this way, the surface of the TaHf layer 2 that is a conductive layer is exposed, and residual oxygen attempts to oxidize the surface of the TaHf layer 2. At this time, it is presumed that the BCl ₃ gas introduced into the etching apparatus collects residual oxygen in the following two ways.

First, BCl ₃ reacts with oxygen to become boron oxide (B _x O _y ) by discharge due to dry etching, thereby collecting residual oxygen and preventing the surface of TaHf layer 2 from being oxidized. It is guessed.

Second, even if the surface of the TaHf layer 2 is oxidized, it is presumed that the oxidized surface is reduced before the influence of oxidation becomes apparent in etching. Further, it is presumed that the etching progresses while reducing the oxidized surface by reducing the oxidized surface and adding the reducing gas to reduce the oxidized surface layer.

As described above, the etching of the pattern portion in the mask blank (first dry etching), or the etching for removing the remaining hard mask layer immediately before the imprint mold fabrication described later (third dry etching) is performed. By introducing a reducing gas when removing the hard mask layer 7, residual oxygen can be eliminated from the etching apparatus very efficiently.

Thereby, as shown in FIG. 1E, a hard mask layer 7 having a fine pattern is formed. Note that the etching end point at this time is determined by using a reflection optical end point detector.
Note that “substantially no oxygen” means “not containing oxygen to the extent that the oxygen content in the etching apparatus is 5% or less”. In addition, performing dry etching using a gas that does not substantially contain oxygen is also simply referred to as dry etching.

(Second dry etching)
Subsequently, after evacuating the gas used in the first dry etching, the quartz substrate 1 is subjected to a second dry etching using a fluorine-based gas in the same dry etching apparatus. At this time, the quartz substrate 1 is etched using the hard mask layer 7 as a mask, and grooves corresponding to the fine pattern shown in FIG. Thereafter, the resist is removed with an alkaline solution or an acid solution.

Examples of the fluorine-based gas used here include C _x F _y (for example, CF ₄ , C ₂ F ₆ , C ₃
F ₈ ), CHF ₃ , mixed gases thereof, or those containing noble gases (He, Ar, Xe, etc.) as additive gases.

Thus, as shown in FIG. 1 (f), the groove processing corresponding to the fine pattern is performed on the quartz substrate 1, and the hard mask layer 7 having the fine pattern is formed on the portion other than the groove of the quartz substrate 1. By removing the resist using an acid solution such as sulfuric acid, the residual hard mask layer pre-removal mold 10 for the imprint mold 20 is produced.

(Third dry etching)
For the mold 10 before removal of the remaining hard mask layer thus manufactured, conventionally, a step of removing the hard mask layer 7 remaining on the mold 10 before removal of the remaining hard mask layer by dry etching (residual hard mask layer). A mask layer removing step) is performed, whereby the imprint mold 20 is manufactured.

However, in the present embodiment, similarly to the first dry etching, the hard mask layer 7 remaining on the mold 10 before the remaining hard mask layer is removed by performing the third dry etching while introducing the reducing gas. Remove.

The basic procedure of the third dry etching, the dry etching gas for removing the hard mask layer, the reducing gas, and the mechanism of the progress of the dry etching are the same as those of the first dry etching described above. That is, in this embodiment, the dry etching gas for removing the hard mask layer is chlorine gas, the reducing gas is BCl _3, and the gas used in the second dry etching is evacuated, and then the chlorine Dry etching is performed while introducing a gas and BCl ₃ gas into the etching apparatus.

After removing the hard mask layer 7 other than the groove forming portion through the third dry etching described above, the substrate 1 is cleaned if necessary. In this way, the imprint mold 20 is completed.

In the present embodiment, the first to third dry etching is performed. However, the dry etching is separately performed according to the hard mask layer constituent materials other than the conductive layer and the antioxidant layer. It may be added during etching.

As shown in FIG. 2, if the imprint mold 20 has a pedestal structure, the following steps may be performed after the formation of the residual hard mask layer removal mold 10 and before the remaining hard mask layer removal step. .
That is, the base structure resist 6 is applied on the mold 10 before removing the remaining hard mask layer in which the groove processing is performed on the quartz, and exposure and development with ultraviolet light are performed (FIG. 2A). Then, the mold 10 before removal of the remaining hard mask layer on which the resist pattern is formed is wet-etched with a mixed solution of hydrofluoric acid and ammonium fluoride, and the resist is removed by predetermined acid cleaning (FIG. 2 ( b)). In this way, the mold 10 before removing the remaining hard mask layer having the pedestal structure is manufactured (FIG. 2C), and the imprint mold 20 is manufactured through the dry etching in which the reducing gas is introduced as described above. Good.

In the manufacturing method of the imprint mold 20 according to the present embodiment as described above, the following effects can be obtained.
First, by using a gas that does not substantially contain oxygen in the dry etching for the hard mask layer 7 and the substrate 1, the amount of oxygen in the etching apparatus is reduced considerably. In addition, the remaining oxygen is further subjected to dry etching in the presence of a reducing gas from the time of pattern formation etching on the hard mask layer 7. Thereby, even if the surface of the conductive layer 2 is oxidized, the oxidized surface of the conductive layer 2 can be reduced before the influence of the oxidation becomes apparent in the etching. In other words, the reductive gas collects the residual oxygen itself, thereby preventing surface oxidation at a considerable portion, and at the same time, returning to the state before oxidation even when the surface is oxidized. Therefore, residual oxygen can be collected very efficiently during dry etching. Moreover, this effect is exhibited not only in dry etching at the time of pattern formation, but also in removing the remaining hard mask layer from the mold before removing the remaining hard mask layer. As a result, dry etching on the hard mask layer 7 can be performed smoothly. As a result, a groove corresponding to a fine pattern can be formed in the substrate 1 with high pattern accuracy, and a high-quality imprint mold 20 can be provided.

Such an imprint mold 20 can be used for thermal imprinting and optical imprinting, and can also be applied to nanoimprint technology. In particular, the present embodiment can be suitably applied to DTR media manufactured using imprint technology.

<Embodiment 2>
In the first embodiment described above, the antioxidant layer 3 made of chromium nitride is provided on the conductive layer 2 made of the tantalum-hafnium alloy layer.
On the other hand, in this embodiment, it is a figure which shows the manufacturing method of the mold 20 for imprinting concerning this embodiment about the case where the antioxidant layer is not provided but the resist layer 4 is provided directly on the conductive layer 2. 3 will be described.

First, as in the first embodiment, the substrate 1 for the imprint mold 20 is prepared (FIG. 3A). The substrate 1 may be a substrate similar to the substrate in the first embodiment. In the present embodiment, description will be made using a disk-shaped quartz substrate 1. Thereafter, the parts that are not specially mentioned are the same as those in the first embodiment.

Next, the quartz substrate 1 is introduced into a sputtering apparatus. Then, a target made of an alloy of tantalum (Ta) and hafnium (Hf) is sputtered with argon gas, and a conductive layer 2 made of tantalum-hafnium alloy is formed on the quartz substrate 1 (FIG. 3B).

Next, a resist for electron beam drawing is applied to the conductive layer 2 to form a resist layer 4 to produce mask blanks used for manufacturing the imprint mold according to this embodiment (FIG. 3). (C)).

Next, a nano-order fine pattern is drawn on the resist layer 4 of the .BR>} blank using an electron beam drawing machine.

After the fine pattern is drawn, the resist layer 4 is developed to form a resist pattern corresponding to the desired fine pattern (FIG. 3D).

(First dry etching)
Next, the substrate 1 having a resist pattern formed on the substrate is introduced into a dry etching apparatus. Normally, even if the first dry etching with chlorine gas containing substantially no oxygen is performed, the surface of the conductive layer 2 is oxidized by the remaining residual oxygen because there is no antioxidant layer. . As a result, the progress of etching is suppressed.

However, as in the first embodiment, in this embodiment, by using a reducing gas in the process of removing the hard mask layer, the residual oxygen in the etching apparatus can be reduced by a considerable amount from the start of dry etching. . Therefore, oxidation of the surface of the conductive layer 2 can be suppressed without providing an antioxidant layer on the conductive layer 2.

The conductive layer 2 having a fine pattern is formed by the first dry etching as described above (FIG. 3E).

(Second dry etching)
Subsequently, after evacuating the gas used in the first dry etching, the quartz substrate 1 is subjected to a second dry etching using a fluorine-based gas in the same dry etching apparatus. At this time, the quartz substrate 1 is etched using the conductive layer 7 as a mask, and a groove corresponding to the fine pattern is formed on the substrate (FIG. 3F). Thereafter, the resist is removed with an alkaline solution or an acid solution.

Thus, as shown in FIG. 3 (f), the groove processing corresponding to the fine pattern is performed on the quartz substrate 1, and the hard mask layer composed only of the conductive layer 7 having the fine pattern is formed on the portion other than the groove of the quartz substrate 1. Thus, the mold 10 before removing the remaining hard mask layer for the imprint mold 20 is produced.

(Third dry etching)
In the present embodiment, the mold 10 before removing the conductive layer is formed on the mold 10 before removing the conductive layer by the third dry etching using a reducing gas in the present embodiment, similarly to the first dry etching. The remaining conductive layer 2 is removed.

The basic procedure of the third dry etching, the dry etching gas and reducing gas for removing the hard mask layer, and the mechanism of the progress of the dry etching are the same as those in the first dry etching and the first embodiment. is there.

After removing the conductive layer 2 remaining on the mold 10 before removing the conductive layer through the above third dry etching, the substrate 1 is washed if necessary. In this way, the imprint mold 20 is completed.

In the manufacturing method of the imprint mold 20 according to the present embodiment as described above, the step of providing an antioxidizing layer can be omitted in the production of mask blanks, and the substance used for the imprint mold Can reduce the kind of. As a result, the processing step for the anti-oxidation layer is not necessary, and the lamination step can be simplified. Ultimately, the manufacturing cost of the imprint mold can be reduced and the yield can be improved.

As mentioned above, although embodiment which concerns on this invention was mentioned, said content of an indication shows illustrative embodiment of this invention. The scope of the present invention is not limited to the exemplary embodiments described above. As described above, for convenience of explanation of the invention, the groove processing is described as line and space in this specification. On the other hand, whether or not it is explicitly described or suggested in this specification, such as a bit pattern in which the remaining portion of groove processing (or groove processing portion) can be a cylindrical shape, etc. Regardless, those skilled in the art can make various modifications to the embodiments of the present invention based on the disclosure of the present specification.

Next, the present invention will be specifically described with reference to examples. Of course, the present invention is not limited to the following examples.

<Example 1> (Method for producing an imprint mold when an antioxidant layer is provided)
In this example, a disc-shaped synthetic quartz substrate (outer diameter 150 mm, thickness 0.7 mm) was used as the substrate 1 (FIG. 1A). This quartz substrate 1 was introduced into a sputtering apparatus. Then, a target made of an alloy of tantalum (Ta) and hafnium (Hf) (Ta: Hf = 80: 20 atomic ratio) is sputtered with argon gas to form a conductive layer 2 made of a tantalum-hafnium alloy having a thickness of 7 nm. (FIG. 1B).

Thereafter, the atmosphere was not exposed to air, and the chromium target was sputtered with a mixed gas of argon and nitrogen to form a chromium nitride layer 3 (chromium: nitrogen = 35: 65 atomic ratio) with a thickness of 2.5 nm. On the quartz substrate 1 on which the hard mask layer 7 having the tantalum-hafnium alloy layer 2 and the chromium nitride layer 3 is thus formed, an electron beam drawing resist film 4 (ZEP520A manufactured by Nippon Zeon Co., Ltd.) is spin-coated to a thickness of 45 nm. Then, baking was performed (FIG. 1 (c)).

Next, a line and space pattern having a periodic structure with a line of 30 nm and a space of 60 nm is drawn on the resist film 4 of the mask blank using an electron beam drawing machine (pressurized voltage 100 kV), and then the resist film 4 is developed. A fine pattern was formed (FIG. 1 (d)).

Next, the substrate 1 on which the hard mask layer 7 having a resist pattern is formed is introduced into a dry etching apparatus, and dry etching (BCl substantially free of oxygen) is introduced while simultaneously introducing BCl ₃ gas and Cl ₂ gas. ₃ : Cl ₂ = 1: 5 (flow rate ratio)). Then, a hard mask layer 7 having a fine pattern composed of a laminate of a tantalum-hafnium alloy film (conductive layer 2) and a chromium nitride layer 3 was formed (FIG. 1 (e)).

Subsequently, after evacuating the gas used in the dry etching for the hard mask layer 7, in the same dry etching apparatus, dry etching using a fluorine-based gas (CHF ₃ : Ar = 1: 9 volume ratio) is performed. This was performed on the quartz substrate 1. At this time, the quartz substrate 1 was etched using the hard mask layer 7 as a mask, and grooves corresponding to a fine pattern were formed on the substrate as shown in FIG.

At this time, the etching time was adjusted so that the groove depth of the substrate 1 was 70 nm. Specifically, etching was performed for 230 seconds. Here, in order to confirm the cross-sectional shape of the pattern, the evaluation blanks produced in the same manner as above were broken and the cross-section of the pattern was observed with a scanning electron microscope. As a result, the resist pattern disappeared and the surface of the chromium nitride layer 3 Was exposed. The film thickness of the chromium nitride layer 3 was reduced to about 1 nm with respect to 2.5 nm before the etching, but the width of the groove of the quartz substrate 1 was changed to the tantalum-hafnium alloy layer 2, the chromium nitride layer 3, and the like. It was confirmed that the width of the fine pattern composed of the hard mask layer 7 having the same is almost the same as that of the fine pattern and that the groove depth of the quartz substrate 1 is uniform.

Then, the resist layer 4 is removed using perhydrosulfuric acid (concentrated sulfuric acid: hydrogen peroxide solution = 2: 1 volume ratio) composed of concentrated sulfuric acid and hydrogen peroxide solution, and the imprint mold 20 in this embodiment is manufactured. A mold 10 for removing the remaining hard mask layer for removal was obtained (FIG. 1 (f)).

After that, after vacuum evacuation, dry etching substantially free of oxygen (BCl ₃ : Cl ₂ =) while simultaneously introducing BCl ₃ gas and Cl ₂ gas into the mold 10 before removing the remaining hard mask layer. 1: 4 (flow rate ratio)). Then, an imprint mold 20 in the present example, in which the hard mask layer 7 on the substrate was removed, was produced (FIG. 1 (g)).

<Example 2> (Method for producing imprint mold when no antioxidant layer is provided)
In this example, a disc-shaped synthetic quartz substrate (outer diameter 150 mm, thickness 0.7 mm) was used as the substrate 1 as in Example 1 (FIG. 3A). This quartz substrate 1 was introduced into a sputtering apparatus. Then, a target made of an alloy of tantalum (Ta) and hafnium (Hf) (Ta: Hf = 80: 20 atomic ratio) is sputtered with argon gas to form a conductive layer 2 made of a tantalum-hafnium alloy having a thickness of 7 nm. (FIG. 3B).

Thereafter, in the present embodiment, an anti-oxidation layer is not provided on the conductive layer 2 and exposure to the atmosphere is not performed. On the quartz substrate 1 on which the conductive layer 2 is formed, a resist film 4 for electron beam drawing (Zeon Corporation) ZEP520A) was applied by spin coating to a thickness of 45 nm and baked (FIG. 3C).

Next, in the same manner as in Example 1, a line and space pattern having a 20 nm periodic structure was drawn on the resist film 4 of the mask blank using an electron beam drawing machine (acceleration voltage 100 kV), and then the resist film 4 was developed. Thus, a fine pattern was formed (FIG. 3D).

Next, the substrate 1 on which the tantalum-hafnium alloy layer 2 having a resist pattern is formed is introduced into a dry etching apparatus, and BCl ₃ gas and Cl ₂ gas are introduced simultaneously, and dry etching substantially free of oxygen is performed. (BCl ₃ : Cl ₂ = 1: 5 (flow rate ratio)). And the conductive layer 2 which has a fine pattern was formed (FIG.3 (e)).

At this time, similarly to Example 1, the etching time was adjusted so that the groove depth of the substrate 1 was 70 nm. Specifically, etching was performed for 270 seconds. Here, in order to confirm the cross-sectional shape of the pattern, the evaluation blanks produced in the same manner as above were broken, and the pattern cross-section was observed with a scanning electron microscope. As a result, the resist pattern disappeared and the tantalum-hafnium alloy layer 2 The surface of was exposed. It was confirmed that the width of the groove of the quartz substrate 1 was almost the same as the width of the fine pattern made of the tantalum-hafnium alloy layer 2 and that the depth of the groove of the quartz substrate 1 was uniform.

Then, the resist layer 4 is removed using perhydrosulfuric acid (concentrated sulfuric acid: hydrogen peroxide solution = 2: 1 volume ratio) composed of concentrated sulfuric acid and hydrogen peroxide solution, and the imprint mold 20 in this embodiment is manufactured. A mold 10 for removing the remaining hard mask layer for removal was obtained (FIG. 3F).

Then, after evacuating, dry etching substantially free of oxygen (BCl ₃ : Cl ₂ = 1: 1) while simultaneously introducing BCl ₃ gas and Cl ₂ gas into the mold 10 before removing the conductive layer. 4 (flow rate ratio)). Then, an imprint mold 20 according to the present example from which the tantalum-hafnium alloy layer 2 on the substrate was removed was produced (FIG. 3G).

<Comparative example>
For comparison with the above-described example, in the comparative example, the hard mask layer was removed without introducing BCl ₃ gas in the etching of the hard mask layer. Other than that, the sample of a comparative example was created like the Example.

<Evaluation>
The imprint molds obtained in Example 1 and the comparative example were observed using a scanning electron microscope. The result is shown in FIG. 4A is a photograph showing the surface of the imprint mold in Example 1, and FIG. 4B is a comparative example.

In Example 1, it was found from FIG. 4A that no oxide film was generated during the removal of the hard mask layer, and etching was performed uniformly.
On the other hand, in the comparative example, it was found from FIG. 4B that an infinite number of oxide films were generated on the substrate and etching was not performed uniformly.

DESCRIPTION OF SYMBOLS 1 Board | substrate 2 Conductive layer 3 Antioxidation layer 4 Resist layer 10 for fine pattern formation Mold before residual hard mask layer removal 20 Imprint mold 6 Resist layer for base structure

Claims

A hard mask layer including a conductive layer made of a compound containing Ta as a main component or at least one element of Hf and Zr or a material containing the compound is formed on a substrate, and a resist layer for pattern formation is formed on the hard mask layer A method for producing an imprint mold, comprising: removing the hard mask layer by dry etching into which a reducing gas has been introduced in the step of removing the hard mask layer from the mask blanks on which is formed.
However, the dry etching is a process using an etching gas not containing oxygen to an extent that the oxygen content in the etching apparatus is 5% or less.
The substrate is a translucent quartz substrate;
The conductive layer is made of Ta and Hf,
The method for producing an imprint mold according to claim 1, wherein the reducing gas contains BCl 3 .
A hard mask layer having a conductive layer made of a compound containing Ta as a main component or at least one element of Hf and Zr or a material containing the compound is formed on a substrate, and a resist layer for pattern formation is formed on the hard mask layer Forming a step;
Developing the resist layer on which a pattern for forming a groove on the substrate is drawn, and then removing the resist layer and the hard mask layer in the groove forming portion by a first dry etching into which a reducing gas is introduced; ,
A step of removing the resist layer in a portion other than the groove forming portion after performing the second dry etching on the translucent substrate of the removed conductive layer portion;
And a remaining hard mask layer removing step of removing a conductive layer in a portion other than the groove forming portion by a third dry etching into which a reducing gas is introduced.
However, the dry etching is a process using an etching gas not containing oxygen to an extent that the oxygen content in the etching apparatus is 5% or less.
The substrate is a translucent quartz substrate;
The conductive layer is made of Ta and Hf,
In the first and third dry etching, a reducing gas containing BCl 3 and a chlorine gas are used,
4. The method for producing an imprint mold according to claim 3, wherein the second dry etching uses a fluorine-based gas or a fluorine-based gas added with a rare gas.
The method for producing an imprint mold according to any one of claims 1 to 4, wherein an antioxidant layer made of chromium nitride is provided on the conductive layer.
On the substrate, a conductive layer made of a compound containing Ta as a main component or at least one element of Hf and Zr or a material containing the compound, an anti-oxidation layer for the conductive layer provided on the conductive layer, Forming a hard mask layer having a pattern forming resist layer on the hard mask layer; and
After developing the resist layer on which a pattern for forming a groove is drawn on the substrate, the resist layer and the hard mask layer where the groove is to be formed are removed by first dry etching in which a reducing gas is introduced. Process,
Performing a second dry etching on the portion of the substrate where the groove is to be formed, and then removing the resist layer in a portion other than the groove forming portion;
A method for producing a mold before removing a remaining hard mask layer, comprising:
However, the dry etching is a process using an etching gas not containing oxygen to an extent that the oxygen content in the etching apparatus is 5% or less.
A conductive layer made of a compound containing Ta as a main component, at least one element of Hf and Zr, or a material containing the compound is provided on at least a part of a substrate having a pattern formed by grooves, and for the conductive layer A mold before removing the remaining hard mask layer, characterized in that a hard mask layer having no anti-oxidation layer is formed.
A hard mask layer having a conductive layer made of a compound containing Ta as a main component, at least one element of Hf and Zr, or a material containing the compound and not having an antioxidant layer for the conductive layer on a substrate. A mask blank formed by forming a resist layer for pattern formation on the hard mask layer.