JP6028413B2 - Method for producing nanoimprint template and template - Google Patents

Description

  The present invention relates to a template manufacturing method and a template used in a nanoimprint method for forming a fine uneven pattern.

  In recent years, particularly in semiconductor devices, high speed operation and low power consumption operation are required due to further progress in miniaturization, and high technology such as integration of functions called system LSIs is required. Under such circumstances, the lithography technology, which is essential for producing semiconductor device patterns, has pointed out the limitations of the photolithographic method due to the problem of exposure wavelength as the device pattern becomes finer, and the exposure apparatus is extremely expensive. It has become to.

  In recent years, the nanoimprint lithography (NIL) method using a fine concavo-convex pattern has attracted attention as an alternative. The nanoimprint method proposed by Chou et al. In Princeton University in 1995 is expected as a technique capable of forming a fine pattern having a high resolution of about 10 nm while the apparatus price and materials used are inexpensive.

  In the nanoimprint method, a template with a nanometer-sized uneven pattern formed on the surface in advance is pressed against a transfer material such as a resin applied and formed on the surface of the substrate to be mechanically deformed to precisely transfer the uneven pattern, This is a technique for processing a substrate to be processed using a patterned nanoimprint material as a resist mask. Once the template is made, the nanostructure can be easily and repeatedly molded, so that high throughput is obtained and it is economical, and since it is a nano-processing technology with less harmful waste, not only semiconductor devices in recent years, Applications in various fields are being promoted.

  As such a nanoimprint method, a thermal nanoimprint method in which a concavo-convex pattern is transferred by heat using a thermoplastic resin, a photo nanoimprint method in which a concavo-convex pattern is transferred by ultraviolet rays using a photocurable material, and the like are known. As the transfer material, a thermoplastic resin is used in the thermal nanoimprint method, and a photocurable material such as a photocurable resin is used in the optical nanoimprint method. The optical nanoimprint method can transfer patterns at room temperature with a low applied pressure, and does not require a heating / cooling cycle like the thermal nanoimprint method and does not cause dimensional changes due to the heat of the template or resin. It is said that it is excellent in terms of sex. Hereinafter, in the present invention, the optical nanoimprint method is simply referred to as a nanoimprint method.

  Conventionally, as a method for producing a template for nanoimprinting, an electron beam resist is applied to the entire surface of a substrate serving as a template, an electron beam drawing is performed on the electron beam resist to form a resist pattern, and the resist pattern is used as an etching mask. A method of manufacturing a template by etching a material to form an uneven pattern is used.

  However, drawing of a fine pattern with an electron beam takes a long time to draw using an expensive drawing apparatus, which raises the problem of increasing the manufacturing cost of the template. In addition, if foreign matter is mixed in the interface between the template and the transferred object during nanoimprinting, both of them are damaged greatly, and the damaged template cannot usually be reused. There was a problem that the produced expensive template was lost.

  Therefore, a replica template manufacturing method has been proposed in which a template manufactured by electron beam lithography is used as a master template as a master template, and a replica template (hereinafter referred to as a replica template) is manufactured from the master template by a nanoimprint method (for example, (See Patent Document 1 and Patent Document 2). This replica template is used for normal nanoimprint on a wafer substrate or the like. Since it is manufactured by the nanoimprint method, the manufacturing cost can be reduced. If multiple replica templates are prepared, the problem of template damage can be dealt with, and the nanoimprint production line using the template can be made into multiple lines. There are advantages.

  However, the conventional replica template manufacturing methods described in Patent Document 1 and Patent Document 2 often involve difficulty in releasing the adhered master template and the transferred substrate after nanoimprinting. Thus, there is a problem that a defect is generated in the transfer pattern or distortion (distortion) is generated in the transfer pattern. This distortion causes deterioration of the “pattern position accuracy” of the transfer pattern. “Pattern position accuracy” is the standard deviation (3σ) of the positional deviation between the ideal lattice and the pattern center defined excluding the isotropic magnification error.

  In order to prevent the occurrence of defects in the mold release process, as shown in FIG. 13, a back surface side opposite to the concavo-convex pattern of the template is processed, and a template whose thickness is changed by reducing the thickness is used. A template that prevents and minimizes gas confinement and / or gas pockets in the pattern layer during the template is disclosed (see Patent Document 3). In addition, in order to correct the distortion of the transferred pattern, a plurality of holding units that hold the peripheral portion of the template and a plurality of holding units are used to control the operation of the driving mechanism based on the distortion information of the transferred pattern. There has been disclosed a stamping device having a mechanism for positioning a portion with respect to a base portion in the Z-axis direction (see Patent Document 4).

Japanese Patent No. 4671860 Japanese Patent No. 4630886 Special table 2009-536591 JP 2010-80714 A

  However, as described in the invention of Patent Document 3, the present inventor performs nanoimprinting using a template having a dent on the back surface and changing the thickness of the nanoimprint region in which the template and the substrate to be processed are in contact ( We found a problem that local pattern distortion occurs near the boundary of the (mesa region). The apparatus described in Patent Document 4 is an invention that forcibly corrects distortion in the XY plane of a transfer pattern using a holding drive mechanism in the XY and Z directions for nanoimprinting on a wafer using a template. However, there is a problem that it is a mechanism that is difficult to cope with with respect to local distortion.

  Therefore, the present invention has been made in view of the above problems. That is, an object of the present invention is to provide a method for manufacturing a template for nanoimprinting, in which a master template is used to manufacture a replica template by nanoimprinting on a substrate to be transferred having a depression on the back surface. It is an object of the present invention to provide a template manufacturing method and a template in which pattern distortion is reduced by removing the template with good pattern position accuracy.

  When the template has a step structure and a depression, the region where the displacement of the transfer pattern of the substrate to be processed is large is a region in contact with the periphery of the step structure (mesa structure) of the template of the substrate to be processed. It has been found that the cause is that distortion occurs in the periphery of the step structure when the pressing force is not appropriate. In the present invention, the peripheral portion of the step structure is previously formed wider than the pattern region, and after forming the uneven transfer pattern on the transfer substrate, the outer peripheral portion having local pattern distortion of the step structure is removed by etching. The pattern position accuracy of the transfer pattern is improved.

  In order to solve the above problems, a method for manufacturing a template for nanoimprinting according to the first aspect of the present invention provides a light-transmitting transfer target substrate having a first main surface and a second main surface. A light curable resin layer is formed on the first main surface, a light transmissive master template having a concavo-convex pattern is pressed against the light curable resin layer, and light is irradiated through the master template to emit the light. Curing the curable resin layer, releasing the master template from the cured photocurable resin layer, forming the cured photocurable resin layer on the first main surface of the transfer substrate, A method for producing a template for nanoimprint, which comprises etching a cured photocurable resin layer and the substrate to be transferred to form a concavo-convex transfer pattern on a first main surface of the substrate to be transferred. However, the second main surface opposite to the first main surface has a recess that overlaps the pattern region of the first main surface and has a larger area than the pattern region of the first main surface. The pattern region of the first main surface forming the transfer pattern has a convex step structure higher than the surroundings, and the step structure has a size larger than the size of the step structure to be finally left including the pattern region. After forming the uneven transfer pattern on the first main surface of the substrate to be transferred, the outer peripheral portion having local pattern distortion of the step structure is removed by etching to remove the step structure. The size of the step structure to be finally left is set as a feature.

  The method for manufacturing a nanoimprint template according to claim 2 of the present invention is the method for manufacturing a replica template for nanoimprint according to claim 1, wherein the shape of the outer peripheral portion of the step structure and the region to be etched are subjected to deformation simulation. And measuring the positional deviation amount, and etching the outer peripheral portion of the step structure after forming the transfer pattern.

  The method for producing a nanoimprint template according to claim 3 of the present invention is the method for producing a replica template for nanoimprint according to claim 1 or 2, wherein an etching is performed on an outer peripheral portion of the step structure. In addition, at least one corner of the outer peripheral portion is included.

  The method for manufacturing a nanoimprint template according to claim 4 of the present invention is the method for manufacturing a nanoimprint template according to any one of claims 1 to 3, wherein the outer peripheral portion of the step structure The etching depth of the region to be etched is in the range of 5 to 30 μm.

  The method for manufacturing a nanoimprint template according to claim 5 of the present invention is the method for manufacturing a nanoimprint template according to any one of claims 1 to 4, wherein the outer peripheral portion of the step structure The length of the region to be etched from the end of the pattern region is increased or decreased according to the shape of the pattern region to be finally left.

  The method for producing a nanoimprint template according to claim 6 of the present invention is the method for producing a nanoimprint template according to any one of claims 1 to 5, wherein the master template is large. The master template is characterized in that a concave and convex pattern is formed on a 6-inch square and 0.25-inch parallel flat quartz substrate and does not have a step structure and a depression.

  The method for producing a nanoimprint template according to claim 7 of the present invention is the method for producing a nanoimprint template according to any one of claims 1 to 6, wherein the substrate to be transferred is: A metal film is formed on the first main surface.

  The method for producing a nanoimprint template according to claim 8 of the present invention is the method for producing a nanoimprint template according to any one of claims 1 to 7, wherein the substrate to be transferred is: It is a quartz glass substrate.

A template for nanoimprinting according to a ninth aspect of the present invention comprises a concavo-convex pattern on the first main surface of a light-transmitting transferred substrate having a first main surface and a second main surface. A template for nanoimprint in which a pattern region is formed, wherein the template overlaps the pattern region of the first main surface on the second main surface opposite to the first main surface, and A recess having a larger area than the pattern region of the first main surface, the pattern region of the first main surface has a convex step structure higher than the surroundings, the step structure is rectangular, and A two-stage structure is formed, the two-stage structure is formed all around the pattern region of the first main surface, and an outer peripheral portion of the step structure is more than a central portion of the step structure forming the uneven pattern. the thickness is rather small, the thickness of the outer peripheral portion The length of at least one side of the small portion from the end of the pattern region is different from the length from the end of the pattern region of the other side .

The template for nanoimprints according to claim 10 of the present invention is the template for nanoimprints according to claim 9, wherein the difference in thickness of the step structure forming the two-stage structure is greater than 5 μm and not more than 30 μm. It is characterized by being.

  According to the method for manufacturing a template for nanoimprinting of the present invention, when a replica template is manufactured by nanoimprinting on a transfer substrate having a recess on the back surface using a master template, a step region is enlarged in advance. In addition, it is possible to manufacture a template with good pattern position accuracy by removing the outer peripheral portion having local pattern distortion generated in the transfer pattern after nanoimprinting by etching.

  In the nanoimprint template of the present invention, a region having a large positional deviation generated in the template manufacturing process is removed by etching, so that a replica template with a positional accuracy close to a master template with little pattern distortion can be obtained.

It is process sectional drawing which shows one Embodiment of the manufacturing method of the template for nanoimprint of this invention. It is process sectional drawing which shows the manufacturing method of the template for nanoimprint of this invention following FIG. It is a plane schematic diagram which shows an example of the manufacturing method of the to-be-transferred substrate used for the manufacturing method of the template for nanoimprinting of this invention shown in FIG. It is a partial plane schematic diagram which shows the magnitude | size relationship between the level | step difference structure in this invention, the level | step difference structure to be finally left, and a pattern area | region. It is the plane schematic diagram and sectional drawing which show one Embodiment of the template for nanoimprints of this invention. It is the plane schematic diagram and sectional drawing which show other embodiment of the template for nanoimprints of this invention. FIG. 6 is a schematic cross-sectional view for explaining deformation of a transferred substrate when a master template is used for nanoimprinting and transferring a pattern onto a transferred substrate having a step structure having a length of 32 mm and a depression. FIG. 6 is a schematic cross-sectional view for explaining deformation of a transferred substrate when a master template is used for nanoimprinting and transferring a pattern onto a transferred substrate having a step structure with a length of 42 mm and a depression. It is a cross-sectional schematic diagram which shows the imprint process of the manufacturing method of the template for nanoimprint in the Example of this invention. It is a figure which shows the displacement (position shift | offset | difference) of the pattern of the replica template in the Example of this invention. It is a figure which shows the position shift of the pattern after deleting the outer peripheral part of the level | step difference structure of the replica template shown in FIG. It is a figure which shows the position shift of the pattern after deleting the outer peripheral part and one corner | angular part of the level | step difference structure of the replica template shown in FIG. It is sectional drawing of the pattern formation apparatus which nanoimprints using the template which has the mesa area | region which has the conventional mesa area | region, and has a dent on the back surface.

  In the present invention, when a replica template is manufactured by nanoimprinting on a transferred substrate having a step structure with a recess on the back surface using a master template, a step region is widened in advance, and a transfer pattern is generated after nanoimprinting. A local pattern distortion is removed by etching, and a template with good pattern position accuracy is manufactured.

  Hereinafter, a nanoimprint template manufacturing method and a nanoimprint template according to an embodiment of the present invention will be described in detail with reference to the drawings.

<Method for producing template for nanoimprint>
(Embodiment 1)
FIG. 1 and subsequent FIG. 2 are process cross-sectional views illustrating an embodiment of a method for producing a nanoimprint template of the present invention.

  As shown in FIG. 1A, a transfer substrate 10 to be processed into a replica template is prepared by the manufacturing method of the present invention. FIG. 1A is a schematic cross-sectional view of an embodiment of a transfer substrate 10.

  In the method for manufacturing a template for nanoimprinting of the present invention, the substrate to be transferred 10 has a first main surface 11 and a second main surface 12, and a pattern region 13 that forms a transfer pattern of the first main surface 11. Has a convex step structure (also referred to as a mesa structure) 14 higher than the surroundings, and a pattern region 13 of the first main surface is formed on the second main surface 12 opposite to the first main surface 11. It has a depression 15 that overlaps and has a larger area than the pattern region 13 of the first main surface. A pattern region 13 for forming a transfer pattern is provided in the step structure 14, and the region of the step structure 14 is formed wider than the pattern region. The region of the step structure 14 is determined based on the simulation and the measurement of the positional deviation amount.

  Unlike the conventional replica template manufacturing method, it is difficult to release the master template and the substrate to be transferred after nanoimprinting, whereas the substrate 10 to be transferred in the replica template manufacturing method of the present invention is difficult. Has a recess 15 having an area larger than that of the pattern region 13 and overlapping with the pattern region 13, so that the transferred substrate 10 is deformed to some extent when it is released from the master template after nanoimprinting. It becomes possible to pull away from the end. In addition, the substrate 10 to be transferred has the effect of extruding air around the uneven pattern even during nanoimprinting, improves the adhesion at the time of transfer with the master template, and suppresses the occurrence of defects. Can be transferred.

  As described above, in order to easily start the mold release, it is only necessary to provide a recess in at least one of the master template and the transfer substrate. However, since the master template forms a pattern by electron beam lithography and uses a photomask manufacturing apparatus for dry etching or the like, it is desirable that the master template has a substrate structure that can easily be adapted to a conventional photomask manufacturing apparatus or mask process. Further, if the recess is provided in the master template, there arises a problem that defects in the master template increase due to an increase in the manufacturing process. Therefore, in the replica template manufacturing method of the present invention, no recess is provided on the master template side, but a recess is provided on the transfer substrate side.

  In the replica template manufacturing method of the present invention, the master template has a concavo-convex pattern on a quartz glass substrate having a 6-inch square and a 0.25-inch parallel plane as a substrate structure suitable for a photomask manufacturing apparatus and a mask process. Is preferably a master template having no step structure and no indentation.

  The shape of the recess 15 of the transferred substrate 10 used in the replica template manufacturing method of the present invention has a shape selected from a group of geometric shapes including a square, a rectangle, a circle, and an ellipse.

  Further, the recess 15 of the transfer substrate 10 includes a bottom surface 16 parallel to the first main surface 11, and the distance (d) from the first main surface 11 to the bottom surface 16 of the recess is the thickness of the transfer substrate 10. It is preferably less than half of (t). By reducing the thickness of the substrate in the indentation region to be smaller than half the thickness (t) of the transferred substrate 10, when the master template and the transferred substrate are released after nanoimprinting, the transferred substrate 10 is removed. This is because elastically deforms and becomes easy to release.

  On the other hand, the lower limit of the distance (d) from the first main surface 11 to the bottom surface 16 of the indentation varies depending on the material of the substrate to be transferred, the indentation region, the shape / area of the step structure, etc., but retains the strength as a template. Therefore, a certain thickness or more is necessary. For example, when a circular recess having a diameter of 60 mm is provided on a 0.25 inch thick quartz glass substrate, the distance (d) is preferably at least 0.5 mm or more.

  In the present invention, a conventionally known spin coating method or inkjet coating method is used as a coating method of the photocurable resin, but the photocurable resin is controlled by controlling the coating amount by dividing the field into predetermined regions. An inkjet method that can be applied is more preferable. This is because in the nanoimprint method, it may be necessary to change the required amount of the photocurable resin to be applied according to the pattern density to be transferred. One field corresponds to one shot size for nanoimprinting.

  The transferred substrate 10 in the replica template manufacturing method of the present invention has a convex step structure (mesa structure) 14 in which the pattern region 13 of the first main surface 11 is higher than the surroundings, thereby forming a step structure. In addition, it is possible to prevent a portion of the substrate to be transferred other than the pattern region from coming into contact with the master template at the time of nanoimprinting and to cause defects or breakage, and to reduce the number of contact portions, thereby facilitating release of the two.

  In the present invention, the step structure 14 is formed wider than the pattern region, and the step structure 14 is preferably wide with a width in the range of about 0.1 mm to 10 mm from the end of the pattern region. If the thickness is less than 0.1 mm, the removal of the pattern distortion is insufficient. On the other hand, if the thickness exceeds 10 mm, the area to be removed by etching becomes wide and the productivity of the template is lowered. The step structure 14 is usually formed by processing the first main surface side of the transfer substrate 10.

  Further, by forming the step structure 14, when the photocurable resin layer is formed on the first main surface 11 of the substrate 10 to be transferred, a field edge is defined, and light is only applied to the mesa structure 14 by the ink jet method. It is easy to apply a curable resin to form a uniform coating layer.

  In the present invention, the length from the pattern region end of the region to be etched of the outer periphery of the step structure is increased or decreased according to the shape of the pattern region to be finally left. That is, when the pattern region is a rectangle, the length from the end of the pattern region is formed longer than the long side with a large distortion compared to the short side. The region of the step structure 14 is determined based on the simulation and the measurement of the positional deviation amount.

  In the replica template manufacturing method of the present invention, it is preferable that the transfer substrate 10 has a metal film formed on the first main surface 11 including the step structure 14. When the transfer substrate 10 is dry-etched to form a transfer pattern, the cured photocurable resin pattern alone may not have sufficient etching resistance. Therefore, it is preferable to use a method in which the cured photocurable resin pattern is converted into a metal film pattern, and the transferred substrate 10 is dry-etched using the metal film as a hard mask.

  As the metal film, chromium or a compound containing chromium (chromium oxide, chromium nitride, chromium oxynitride, etc.) having high resistance to a fluorine-based gas used when etching a quartz glass substrate or the like to be transferred substrate 10 is preferable. The film thickness is in the range of about 10 nm to 80 nm.

(Transfer substrate manufacturing method)
Here, a manufacturing method of the transfer substrate 10 used in the manufacturing method of the replica template of the present invention will be described with reference to the drawings. FIG. 3 is a process cross-sectional view illustrating an example of a manufacturing process of the transfer substrate 10 used in the replica template manufacturing method of the present invention. In FIG. 3, when the same part as FIG. 1 is shown, the same code | symbol is used.

  As shown in FIG. 3A, a transfer substrate 10a having a first main surface 11 and a second main surface 12 is prepared.

  Next, as shown in FIG. 3B, a transfer substrate 10 b having a convex step structure (mesa structure) 14 higher than the surrounding is formed on the first main surface 11. As will be described later, the pattern region 13 is provided on the step structure 14, and as described above, the step structure 14 is formed wider than the pattern region. The step structure 14 can be formed by wet etching using a hydrofluoric acid aqueous solution, with a predetermined region of the substrate 10a to be transferred masked in advance with a resist pattern or a pattern of a resist and a metal film such as chromium.

  The shape of the step structure (mesa structure) 14 is usually rectangular from the viewpoint of wafer production efficiency, but is not necessarily limited, and the shape may be other shapes or indefinite. The height of the convex step structure is provided in the range of several μm to several tens of μm. The area of the pattern region 13 having the step structure depends on a required pattern of one field, but is set to a rectangular shape of several tens mm × several tens mm, for example.

  Next, the second main surface 12 of the substrate to be transferred 10b is processed by a conventionally known method such as counterboring to form a recess 15, and the first main surface is formed as shown in FIG. 11 pattern region 13 has a convex step structure 14 higher than the surrounding, and overlaps with the second main surface 12 opposite to the first main surface 11 with the pattern region 13 of the first main surface. In addition, the transfer substrate 10 having the depression 15 having a larger area than the pattern region 13 on the first main surface is formed.

  In the present invention, examples of the material constituting the transferred substrate 10a shown in FIG. 3A include optically polished quartz glass, soda glass, fluorite, and calcium fluoride that transmit light used for nanoimprinting. Quartz glass has a proven track record as a photomask substrate and is stable in quality, and can be integrated into a light-transmitting structure by providing a step structure, indentation, and concavo-convex pattern. Since a fine uneven | corrugated pattern can be formed, it is more preferable.

Again, returning to FIG.
As shown in FIG. 1B, a photocurable resin layer 17 is formed on the step structure 14 on the first main surface 11 of the prepared substrate 10 to be transferred. On the other hand, a master template 18 provided with an uneven pattern 19 to be transferred is prepared.

  Next, as shown in FIG. 1C, the photocurable resin layer 17 on the step structure 14 of the substrate to be transferred 10 and the concave / convex pattern 19 of the master template 18 are brought into close contact with each other, and light (ultraviolet light) 20 is pressed. Is applied to cure the photocurable resin layer.

  Next, the master template 18 is released from the cured photocurable resin. After the mold release, as shown in FIG. 1D, a transfer pattern is formed by the cured photocurable resin 21 on the step structure 14 on the first main surface 11 of the transfer substrate 10.

  In the nanoimprint method, a portion of the photocurable resin corresponding to the convex portion of the concave / convex pattern of the master template 18 remains as a thin residual film on the substrate to be transferred, so oxygen gas was used as shown in FIG. The thin residual film is removed by ion etching or the like to form a cured photocurable resin pattern 22.

Next, using the photocurable resin pattern 22 as a mask, the transferred substrate is dry-etched using CF ₄ gas or the like, and then the photocurable resin pattern is removed. As shown in FIG. A replica template 24a is obtained in which a concavo-convex transfer pattern 23 is formed in the pattern region of the main surface 11 of the main surface 11. When dry etching is performed, the surface of the transfer substrate other than the step structure 14 is masked to protect it from being etched.

  Next, as shown in FIG. 2 (g), a resist is applied to the entire surface of the first main surface of the replica template 24a, exposed and developed to form a resist pattern 25, and a predetermined region to be etched is formed. The outer peripheral portion 26 of the step structure is exposed. As the resist, an electron beam resist, a photosensitive resist, or the like can be used.

  Next, the outer peripheral portion 26 of the step structure exposed from the resist is etched, the resist pattern 25 is peeled off, and the outer peripheral portion 26 of the step structure has an outer peripheral portion having a predetermined etching depth as shown in FIG. 27, and a nanoimprint replica template 24 having an uneven transfer pattern 23 is formed. Either wet etching or dry etching can be applied to the outer peripheral portion 26 of the step structure. However, when the substrate to be transferred is a quartz substrate, wet etching using a hydrofluoric acid aqueous solution capable of deep etching is preferable.

  The etching process of the outer peripheral portion 26 of the step structure is not limited to the above method. For example, the use of a metal thin film in addition to the resist film as an etching mask, the formation of a resist film pattern for etching by a nanoimprint method, and dry etching A method such as outer peripheral etching by a method can be used as appropriate.

  In the template manufacturing method of the present invention, the region to be etched of the outer peripheral portion 26 of the step structure measures the amount of positional deviation from the design value of the transfer pattern on which the replica template 24 shown in FIG. It is preferable to predetermine the etching width or the like. The measurement of the pattern displacement amount can use a conventional commercially available coordinate measuring device for a photomask. In addition, when a plurality of identical replica templates are manufactured under a constant template manufacturing condition, it is possible to provide an etching region width in advance.

  Here, the step structure region of the transfer substrate in the present invention, the step structure region to be finally left as a template by etching and removing the outer periphery of the step structure region, and the pattern region are used with reference to the drawings. I will explain. FIG. 4 is a partial plan view schematically showing the size relationship between the step structure, the step structure desired to be finally left, and the pattern region. The size relationship of the plane areas of the three regions is as follows (step structure (A) of the transferred substrate)> step structure (B) to be finally left (template) ≧ pattern region (C).

The region of the step structure (A) includes a region that is additionally widened with respect to the region of the step structure (B) to be finally left in consideration of the distortion generated in the outer peripheral portion during transfer. In addition, when the measurement and simulation of the position accuracy are separately performed and the improvement of the position accuracy is confirmed by removing the additionally widened area, there is no pattern in the additionally widened area. Also good.
The region of the step structure (B) to be finally left is the same as or close to the desired C pattern region, and is appropriately selected so as to have a higher density when performing multiple transfer by step-and-repeat (S & R). It has a decided size.
The pattern area (C) is an area including a circuit pattern, an alignment mark, a position accuracy measurement mark, a dummy pattern, and the like.

  Although the width of the etching region varies depending on the size of the step structure 14 and the size of the pattern region, as described above, the width of the step structure 14 is usually about 0.1 mm to 10 mm from the end of the pattern region. Since the width is wide in the range, the etching width is preferably provided in a range of about 0.1 mm to 10 mm from the boundary of the outer periphery of the step structure toward the center of the step structure. This is because if the etching width is less than 0.1 mm, the removal of the pattern distortion generated in the peripheral portion of the step structure is insufficient, while if it exceeds 10 mm, the area to be removed by etching becomes wide, which reduces the productivity of the template. .

  In the present invention, the step structure becomes a two-step structure by etching, and the etched outer peripheral portion 27 having a predetermined etching depth has a thickness smaller than that of the central portion 28 of the step structure forming the uneven pattern. is there.

  The etching depth of the region to be etched in the outer peripheral portion of the step structure is preferably in the range of 5 μm to 30 μm. This is because, if the etching depth is less than 5 μm, it is not sufficient to remove the pattern distortion generated in the peripheral portion of the step structure, and if it exceeds 30 μm, the etching also becomes difficult because side etching becomes large.

(Functional effects by etching the outer periphery of the step structure)
FIGS. 7A and 7B show a case where a master substrate 71 is used to transfer a pattern by nanoimprinting onto a transferred substrate 72 having a step structure (mesa structure) having a length of 32 mm and a depression. It is a cross-sectional schematic diagram explaining the deformation | transformation. FIG. 7B is an enlarged view in which the size of the horizontal component of deformation near the boundary of the step structure in the circle shown in FIG. 7A is displayed in black and white density. The black and white density indicating the deformation in the horizontal direction is obtained by simulation (referred to as deformation simulation in the present invention). The higher the black density, the larger the deformation in the left direction indicated by the arrow in FIG. The lower the value, the greater the deformation in the right direction.

  As shown in FIG. 7, when the pressing force of the master template 71 to the transfer substrate 72 is strong, stress is generated near the boundary 74 of the nanoimprint region (step structure region) 73 where the template 71 and the transfer substrate 72 are in contact with each other. Are concentrated and deformed. As a result, when the deformation is locally generated around the boundary 74 of the step structure and the load (pressing force) is released, the outward pattern toward the outer periphery of the step region 73 is opposite to the deformation indicated by the arrow. The displacement will remain. Conversely, when the load adjustment results in a negative load, an inward pattern displacement toward the center may remain. In FIG. 7, the horizontal component of the template deformation is shown, but the deformation is also generated in the vertical direction (not shown).

  FIG. 8 illustrates the deformation of the transferred substrate 82 when the master template 81 is used and each template is nano-imprinted and transferred onto the transferred substrate 82 having a step structure (mesa structure) having a length of 42 mm and a recess. It is a cross-sectional schematic diagram. Conditions other than the length of the step structure in FIGS. 7 and 8 are the same. FIG. 8B is an enlarged view in which the size of the horizontal component of the deformation near the boundary of the step structure in the circle shown in FIG. As is clear from a comparison between FIG. 7B and FIG. 8B, when the length of the step structure of FIG. 8 is as long as 42 mm, the length outside the nanoimprint region that can move freely is shortened. The deformation in the vicinity of the boundary 84 of the nanoimprint region (step structure region) 83 where the template 81 and the transfer substrate 82 are in contact with each other is smaller than the case where the length of the step structure of FIG. 7 is 32 mm. I understand.

  Therefore, in the manufacturing method of the present invention, the length from the pattern region end of the region to be etched on the outer periphery of the step structure is increased or decreased according to the shape of the pattern region to be finally left, and near the boundary of the step structure. It is preferable to control so as to reduce the deformation.

  The replica template manufacturing method of the present invention is capable of manufacturing a template with good pattern position accuracy by removing, by etching, pattern distortion locally generated around the boundary of the step structure after nanoimprinting.

  The replica template transfer pattern positional deviation amount can be brought close to the master template pattern positional deviation amount by removing the peripheral part of the step structure after nanoimprinting, and the replica template has almost the same pattern positional accuracy as the master template. Can also be manufactured.

  In the present invention, the depth of the concave portion of the concave / convex pattern 23 formed by digging the stepped structure of the transferred substrate 10 is the thickness of the desired resin pattern of the photocurable resin pattern formed on the nanoimprint substrate such as a wafer substrate. For example, the depth of the concave portion of the concavo-convex pattern 23 is used in the range of 20 nm to 100 nm.

  In the manufacturing method of the present invention, as shown in FIG. 2 (h), the uneven pattern 23 of the obtained replica template 24 is the uneven relationship, left-right relationship of the uneven pattern 19 of the master template 18 shown in FIG. 1 (b). Becomes a reversed pattern. Therefore, if the master template pattern data is converted in advance corresponding to the required replica template pattern, and the replica template is produced using a master template having a pattern in which the concavo-convex relationship and the left-right relationship are reversed, it is necessary. A replica template having a desired pattern can be obtained. The method of previously converting the pattern data is a preferable method in which the replica template manufacturing process is not burdened and the occurrence of defects does not increase.

(Embodiment 2)
In the template manufacturing method of the present embodiment, at least one corner portion of the outer peripheral portion is included in the region to be etched of the outer peripheral portion of the step structure described in the first embodiment. This is because large pattern distortion often occurs not only at the outer periphery of the step structure but also at the corners. In addition to the outer peripheral portion of the step structure, a template with good pattern position accuracy can be manufactured by etching corner portions of one or more outer peripheral portions having a large pattern distortion.

  As for the corners of the outer peripheral part to be etched, the positional deviation amount from the design value of the transfer pattern formed with the replica template 24a shown in FIG. It is preferable to define the above. In addition, when manufacturing a plurality of the same replica templates under a constant template manufacturing condition, it is possible to set corners and etching widths to be etched in advance.

  As described above, the method for manufacturing a template for nanoimprinting of the present invention uses a master template to prepare a step region in advance when a replica template is manufactured by nanoimprinting on a transferred substrate having a step structure with a depression on the back surface. It is possible to manufacture a template with good pattern position accuracy by removing the local pattern distortion generated in the transfer pattern after nanoimprinting by etching.

<Template for nanoimprint>
FIG. 5 is a schematic plan view and a schematic cross-sectional view showing an embodiment of a nanoimprint template of the present invention, and FIG. 6 is a schematic plan view and a schematic cross-sectional view showing another embodiment. 5 and 6, the same reference numerals are used to indicate the same parts as those in FIGS.

(Embodiment 1)
The nanoimprint replica template of this embodiment is the template 24 shown in FIG. 2 (h) manufactured in the first embodiment of the method for manufacturing a nanoimprint template. 5A is a schematic plan view of the template 24, and FIG. 5B is a schematic cross-sectional view taken along the line DD in FIG. 5A. The template 24 shown in FIG. 5 exemplifies a case where the recess 15 is square and the step structure and the pattern area are square.

  As shown in FIG. 5, a pattern region including a concavo-convex pattern 23 is formed on the first main surface 11 of the transfer substrate having the first main surface 11 and the second main surface 12. The second main surface 12 opposite to the first main surface 11 includes a recess 15 that overlaps the pattern region of the first main surface 11 and has a larger area than the pattern region of the first main surface 11; A step structure in which the pattern region of the first main surface 11 has a convex step structure (mesa structure) higher than the surroundings, the step structure has a two-step structure, and the outer periphery of the step structure forms an uneven pattern. It is a template whose thickness is smaller than the central part.

(Embodiment 2)
In the template shown in FIG. 6, a pattern region including a concavo-convex pattern 23 is formed on the first main surface 11 of the transferred substrate having the first main surface 11 and the second main surface 12. 6A is a schematic plan view of the template 24, and FIG. 6B is a schematic cross-sectional view taken along line EE in FIG. 6A. The second main surface 12 opposite to the first main surface 11 includes a recess 15 that overlaps the pattern region of the first main surface 11 and has a larger area than the pattern region of the first main surface 11; The recess 15 has a circular shape, the pattern region of the first main surface 11 has a convex step structure (mesa structure) higher than the surroundings, the pattern region has a square shape, and the step structure has a two-step structure. None, the outer peripheral portion of the step structure is smaller in thickness than the central portion of the step structure forming the concavo-convex pattern, and the four corners of the square outer peripheral portion of the step structure are removed.

  The template according to the present embodiment can be a template with good pattern position accuracy by etching the corners at the four outer peripheral portions where pattern distortion is large in addition to the outer peripheral portion of the step structure.

The constituent material, the shape of each part, and the representative dimensions of the template 24 of the above embodiment are the same as those described in the above manufacturing method, and thus the description thereof is omitted.
Next, an example explains the present invention.

Example 1
As a substrate to be transferred for a replica template for nanoimprint, a step structure (mesa) having an area of 28 mm × 32 mm, which is 30 μm higher than the surrounding, is formed on a first main surface of a synthetic quartz glass substrate having an outer shape of 6 inches square and a thickness of 0.25 inches. And a second main surface having a circular recess with a diameter of 60 mm that overlaps with the pattern region of the first main surface and has a larger area than the pattern region of the first main surface. Prepared. The aim of the final step structure (mesa structure) was 25 mm × 30 mm, and the area to be removed by etching was calculated in advance by simulation, and the long side was 1 mm on one side and the short side was 1.5 mm on one side. The thickness of the quartz glass substrate where the depression was formed was 1 mm.

On the other hand, as a master template for nanoimprinting, an electron beam resist is applied at a thickness of 200 nm on one main surface of a synthetic quartz glass substrate having a 6-inch square and a thickness of 0.25 inch, drawn with an electron beam, and developed. After forming the resist pattern, the quartz glass was dry-etched with CF ₄ gas, and then the resist pattern was peeled off to produce a master template in which an uneven pattern was formed on the quartz glass.

  The depth of the concave portion of the pattern of the produced master template was 50 nm. The patterns were two patterns: a plurality of line and space patterns with a recess width of 40 nm and a pitch of 80 nm, and a plurality of line and space patterns with a recess width of 30 nm and a pitch of 60 nm. The master template pattern is obtained by presetting a pattern obtained by inverting the concavo-convex relationship and the left-right relationship of the required replica template pattern.

  Next, a photocurable resin for nanoimprinting was applied to the mesa structure of the above-described transfer substrate by an inkjet method for one field. Subsequently, the master template is used to press the photocurable resin layer on the substrate to be transferred and to irradiate the photocurable resin through the master template with ultraviolet light that sensitizes the photocurable resin. Cured. FIG. 9 is a schematic cross-sectional view when the master template 91 is pressed against the photocurable resin layer 93 of the transfer substrate 92.

  Next, a release force was applied downward from two opposing end faces of the transfer substrate to release the transfer substrate from the master template. The transferred substrate has a dent, and can be separated from the end surface of the transferred substrate by being deformed to some extent. The uneven pattern of the photocurable resin is transferred onto the substrate to be transferred, and the photocurable resin pattern does not ooze out from the field on the mesa structure, and the photocurable resin has a height of 50 nm and the remaining film thickness in the field. A pattern with a uniform film thickness of 15 nm was formed.

  Next, the photocurable resin remaining as a thin residual film on the substrate to be processed is removed by ion etching using oxygen gas, and the photocurable resin pattern having a height of 35 nm is cured on the substrate to be processed. Formed.

Next, using the photocurable resin pattern as a mask, the quartz glass of the substrate to be processed is dry-etched using CF ₄ gas, and then the photocurable resin pattern is peeled off to form a pattern region on the mesa structure of the first main surface In addition, a replica template having an uneven transfer pattern made of quartz glass was obtained. The pattern of the replica template is a pattern in which the concavo-convex relationship and the left-right relationship are reversed with the pattern of the master template, and on the mesa structure, a plurality of line and space patterns having a recess depth of 50 nm, a recess width of 40 nm, and a pitch of 80 nm, It has two patterns, that is, a plurality of line and space patterns having a recess width of 30 nm and a pitch of 60 nm.

  Next, the amount of positional deviation from the design value of the pattern of the replica template was measured with a photomask coordinate measuring device (manufactured by KLA Tencor). The result is shown in FIG. 10 as the displacement of the position coordinates. FIG. 10A shows the displacement of the position coordinates when the transfer pattern area in the replica template before removing the outer peripheral portion by etching (denoted as “deletion”) is 27 mm × 31 mm, the direction of the arrow is the direction of the displacement, The size of the arrow indicates the magnitude of the displacement. An inward displacement of the pattern area has occurred, and the displacement of the outer periphery of the pattern area is particularly large. FIG. 10B shows the maximum value, minimum value, and standard deviation (3σ) of the displacement (nm) of the position coordinates (X, Y) of the pattern of the replica template. FIG. 10C shows the displacement (nm) of the position coordinates (X, Y) of the pattern of the master template, and it is shown that the positional deviation of the replica template is large by comparing with the replica template.

  Next, based on the above result, the displacement of the position coordinate when the outer peripheral portion of the pattern area where the displacement of the position coordinate is particularly large was deleted was obtained by calculation. The width (one side) of the deleted outer peripheral portion is 1.5 mm in the X direction and 1.0 mm in the Y direction. FIG. 11 shows the result. FIG. 11A shows the displacement of the position coordinates when the transfer pattern area is 23.5 mm × 28.3 mm, and FIG. 11B shows the maximum value and the minimum value of the displacement (nm) of the position coordinates (X, Y). Standard deviation (3σ). As shown in FIG. 11A, the large displacement is removed by deleting the outer peripheral portion of the pattern area, and the displacement of the position coordinates (X, Y) shown in FIG. 11B approaches the value of the master template. It was confirmed that a template with good positional accuracy was obtained.

  Next, a photoresist is applied to the entire surface of the first main surface of the replica template, and based on the simulation results, the outer peripheral portion of the step structure has a width on one side of 1.5 mm in the X direction and 1.0 mm in the Y direction. The pattern was exposed so as to be exposed, and developed to form a resist pattern.

  Next, the outer peripheral portion of the step structure exposed from the resist is etched to a depth of 10 μm with a hydrofluoric acid aqueous solution, and then the resist pattern is peeled off, and the outer peripheral portion has a width of one side of 1.5 mm in the X direction and the Y direction. A replica template having a two-level step structure etched at 1.0 mm was obtained.

  In the template manufacturing method of the present embodiment, a high-quality replica template that is close to the value of the master template can be obtained by removing a region with a large misalignment generated in the replica template manufacturing process by etching. It was.

(Example 2)
When the upper right corner (corner portion) of the outer peripheral portion of the pattern region where the displacement of the position coordinates is still particularly large in FIG. 11A is further deleted by simulation based on the replica template obtained in the first embodiment. The displacement of the position coordinate was obtained.

  The deleted corner is a right-angled isosceles triangle with a side of 1 mm. FIG. 12 shows the result. 12A shows the displacement of the position coordinates, and FIG. 12B shows the maximum value, minimum value, and standard deviation (3σ) of the displacement (nm) of the position coordinates (X, Y). As shown in FIG. 12A, a large displacement is removed by deleting the corners of the outer periphery of the pattern area when the transfer pattern area is 23.5 mm × 28.3 mm, and the position coordinates ( The displacement of (X, Y) was almost the same as the value of the master template, and it was confirmed that a template with reduced pattern displacement was obtained.

  In the same manner as in Example 1, a resist pattern in which the corners of the outer periphery of the step structure of the replica template are exposed is formed, the corners are etched to a depth of 10 μm with a hydrofluoric acid aqueous solution, and then the resist pattern is peeled off Then, a replica template having a two-step structure in which the outer peripheral portion was etched with a width of one side of 1.5 mm in the X direction and 1.0 mm in the Y direction and one corner portion was etched was obtained.

  In the template manufacturing method of this embodiment, a high-quality replica with little pattern distortion and almost the same pattern positional accuracy as that of the master template is removed by etching an area with a large positional deviation generated in the replica template manufacturing process. A template was obtained.

10, 10a, 10b Transfer target substrate 11 First main surface 12 Second main surface 13 Pattern region 14 Step structure (mesa structure)
15 Indentation 16 Indentation bottom surface 17 Photocurable resin layer 18 Master template 19 Uneven pattern 20 Light (ultraviolet light)
21 cured photocurable resin 22 cured photocurable resin pattern 23 uneven transfer pattern 24, 24a replica template 25 resist pattern 26 outer peripheral portion 27 of step structure outer peripheral portion 28 of predetermined etching depth central portion A of step structure Step structure B Step structure C to be finally left Pattern regions 61, 71, 81 Master templates 62, 72, 82 Substrate to be transferred 63, 73, 83 Nanoimprint (step structure) regions 64, 74, 84 Step structure boundary 91 Master Template 92 Transferred substrate 93 Photocurable resin layer 131 Pattern forming device 132 Substrate 133 Stage 134 Mold 135 Template chuck 136 Polymer material 137 Actuator system

Claims (10)

Light having a photocurable resin layer formed on the first main surface of a light transmissive transfer substrate having a first main surface and a second main surface, and having a concavo-convex pattern on the photocurable resin layer. Pressing a transparent master template, irradiating light through the master template to cure the photocurable resin layer, releasing the master template from the cured photocurable resin layer, the transferred object Forming the cured photocurable resin layer on the first main surface of the substrate, etching the cured photocurable resin layer and the transferred substrate, and forming irregularities on the first main surface of the transferred substrate; A method for producing a nanoimprint template for forming a transfer pattern of
The transferred substrate overlaps the pattern region of the first main surface on the second main surface opposite to the first main surface and has a larger area than the pattern region of the first main surface. The pattern region of the first main surface forming the transfer pattern has a convex step structure that is higher than the surroundings.
The step structure is formed to be wider than the size of the step structure to be finally left including the pattern region,
After forming the concavo-convex transfer pattern on the first main surface of the substrate to be transferred, the outer peripheral portion having local pattern distortion of the step structure is removed by etching, and the step structure where the step structure is to be left finally is left. The manufacturing method of the template for nanoimprint characterized by setting it as the size of a structure.   The shape of the outer periphery of the step structure and the region to be etched are determined by deformation simulation and measurement of a displacement amount, and the outer periphery of the step structure is etched after the transfer pattern is formed. Manufacturing method of nanoimprint template.   The method for producing a nanoimprint template according to claim 1, wherein at least one corner of the outer peripheral portion is included in the region to be etched of the outer peripheral portion of the step structure.   The method for producing a template for nanoimprint according to any one of claims 1 to 3, wherein an etching depth of a region to be etched in the outer peripheral portion of the step structure is in a range of 5 µm to 30 µm. .   5. The length from the edge of the pattern region of the region to be etched in the outer peripheral portion of the step structure is increased or decreased according to the shape of the pattern region to be finally left. The manufacturing method of the template for nanoimprint any one of the above.   The master template is a master template having a concave and convex pattern formed on a parallel flat quartz substrate having a size of 6 inches square and a thickness of 0.25 inches, and having no step structure and depressions. The manufacturing method of the template for nanoimprints of any one of Claim 1- Claim 5.   The method for producing a nanoimprint template according to any one of claims 1 to 6, wherein a metal film is formed on the first main surface of the substrate to be transferred.   The said imprinted substrate is a quartz glass substrate, The manufacturing method of the template for nanoimprints of any one of Claim 1-7 characterized by the above-mentioned. A template for nanoimprint in which a pattern region made of a concavo-convex pattern is formed on the first main surface of a light-transmitting transferred substrate having a first main surface and a second main surface,
The template overlaps the second main surface opposite to the first main surface with the pattern region of the first main surface and has a larger area than the pattern region of the first main surface. The pattern region of the first main surface has a convex step structure higher than the surroundings,
The step structure is rectangular and has a two-stage structure, the two-stage structure is formed all around the pattern area of the first main surface, and the outer periphery of the step structure has the uneven pattern. the formed rather smaller thickness than the central portion of the stepped structure, the length of the at least one side of the pattern area end of the thickness of a small portion of the outer peripheral portion is different from the length of the pattern area end of another side A template for nanoimprint, which is characterized by that. 10. The nanoimprint template according to claim 9, wherein a difference in thickness of the step structure forming the two-stage structure is in a range of greater than 5 μm and less than or equal to 30 μm.

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