JP2013193326A - Pattern forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pattern forming method capable of recycling a template of high precision.SOLUTION: A pattern forming method being a pattern forming method of forming a pattern using a first template having at least one of recessed or projection parts, includes steps of: forming a transfer pattern on a substrate by coating the substrate with a resin and transferring the shape of the first pattern of the first template to the resin; cleaning the first template; inspecting the first template; and returning to the steps of: forming the transfer pattern when a preset condition is met as the result of inspection on the first template; and correcting the first pattern of the first template with a filling material using a second template having a second pattern formed by reversing ruggedness of the first pattern when the condition is not met.

Description

  Embodiments described herein relate generally to a pattern forming method.

  In pattern formation, an imprint method using an original plate (template) having a concavo-convex shape has attracted attention. Among imprint methods, a technique for forming a particularly fine pattern, such as manufacturing a semiconductor integrated circuit, is said to be a nanoimprint lithography technique (hereinafter simply referred to as “nanoimprinting”). In nanoimprinting, a template on which a concavo-convex shape corresponding to a pattern of a semiconductor integrated circuit or the like is formed is imprinted on a resist applied on a substrate such as a semiconductor wafer. Transfer to resist.

  In the imprint method, since the template is repeatedly used, a pattern that forms the uneven shape of the template, a foreign matter, or the like occurs during use. If the template has a pattern defect or foreign matter attached, the shape of the defective pattern or the shape of the foreign substance is transferred to the resist. For this reason, when a pattern defect occurs or a foreign substance that cannot be removed by washing adheres, the template is discarded.

JP 2007-313880 A

  Embodiments of the present invention provide a pattern forming method capable of reusing a highly accurate template.

  The pattern forming method according to the embodiment is a pattern forming method of forming a pattern using a first template having a first pattern having at least one of a concave portion and a convex portion, and applying a resin on a substrate, A step of transferring the shape of the first pattern of the first template to the resin to form a transfer pattern on the substrate; a step of cleaning the first template; and a step of inspecting the first template. As a result of the inspection of the first template, when the preset condition is satisfied, the process returns to the step of forming the transfer pattern, and when the condition is not satisfied, the unevenness of the first pattern is inverted. Modifying the first pattern of the first template with a filling material using a second template having a second pattern.

It is a flowchart which illustrates the pattern formation method which concerns on this embodiment. It is a flowchart which illustrates the pattern formation method which concerns on a reference example. (A)-(c) is typical sectional drawing which illustrates the correction method (the 1) of the workpiece template. (A) And (b) is a figure which shows the example which forms a sub replica template for every block. It is a schematic diagram which illustrates the mother template by which the area | region of the pattern was divided | segmented. (A)-(e) is typical sectional drawing which illustrates the correction method (the 2) of the work template. (A) And (b) is typical sectional drawing illustrated about the shape of a concave pattern.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between the parts, and the like are not necessarily the same as actual ones. Further, even when the same part is represented, the dimensions and ratios may be represented differently depending on the drawings.
Further, in the present specification and each drawing, the same reference numerals are given to the same elements as those described above with reference to the previous drawings, and detailed description thereof will be omitted as appropriate.

(First embodiment)
The pattern forming method according to the present embodiment is a method of forming a pattern using a work template (first template) having a first pattern having at least one of a concave portion and a convex portion.

  First, a mother template, a substantial replica of the mother template (replica template), and a work template used for imprinting are prepared. The replica template (second template) is provided with a second pattern obtained by inverting the irregularities of the first pattern of the work template.

  Next, imprinting is performed using the work template. That is, a resin is applied on the substrate, the shape of the pattern of the work template is transferred to the resin, and a transfer pattern is formed on the substrate. After imprinting, the workpiece template is cleaned for the purpose of removing foreign matter. Next, a defect inspection is performed to inspect whether the work template is damaged or the like.

  In this defect inspection, if damage (for example, pattern dimension narrowing, pattern defect), etc. is detected in the work template pattern, and the template is out of specification at a certain point in time, it will be compensated using a replica template. To correct the first pattern of the work template.

  Until now, if the template was out of specification in terms of quality, the template was discarded and a new template was produced, but in this embodiment, the work template is prepared using a replica template prepared in advance. Restoring the missing part of the pattern and the thin part of the pattern (a phenomenon in which the width of the convex pattern itself narrows) is restored. As a result, the work template can be used for a long time without being discarded.

Next, details of a pattern forming method by imprinting will be described.
FIG. 1 is a flowchart illustrating a pattern forming method according to this embodiment.
FIG. 2 is a flowchart illustrating the pattern forming method according to the reference example.
First, the flow of the pattern forming method according to the reference example will be described with reference to FIG.
As shown in FIG. 2, the pattern forming method according to the reference example includes template production (step S201), imprint (step S202), determination of cleaning conditions (step S203), template cleaning (step S204), defect inspection ( Step S205) and template destruction (Step S206) are provided.

<Step S201: Template production>
In the production of the template shown in step S201, a master template and a work template are produced.
To produce a master template, first, mask data is generated based on design data. Next, for example, an electron beam (EB) exposure apparatus draws a 1 × (equal size) pattern on a quartz (QZ) substrate coated with an EB resist to form a pattern. Thereafter, the resist for EB is developed and the QZ substrate is etched to form a mask pattern on the QZ substrate. Thereby, the master template in which the mask pattern is formed on the QZ substrate is completed.

  In order to manufacture a work template, first, a resist pattern is formed on a QZ substrate by an imprint method using a master template. Next, by etching the QZ substrate through the resist pattern, a work template having a pattern formed on the QZ substrate is completed.

<Step S202: Imprint>
In the imprint shown in step S202, a pattern is transferred onto, for example, a wafer substrate using the work template. As an example, by pressing a work template on which a concavo-convex pattern corresponding to the pattern of a semiconductor integrated circuit is formed on a resist applied to a semiconductor wafer, the shape of the concavo-convex pattern formed on the work template is used as a resist. Transcript.

  In the manufacture of a semiconductor integrated circuit, for example, the above-described imprint is repeatedly performed on a single semiconductor wafer while changing the location (step & repeat). After imprinting for one semiconductor wafer, similar imprinting may be repeated for the next semiconductor wafer.

  In the imprint method, patterning is performed via a resist between a work template and a substrate such as a semiconductor wafer. As the imprint process is repeated, dirt on the work template and foreign matter on the uneven portions of the template pattern are removed. Pinching and sticking of resist and other foreign matters may occur. In addition, the template for the workpiece itself may be caused by various factors, such as the template pattern being lost due to foreign matter adhering to the substrate such as a semiconductor wafer, frictional force generated at the time of stamping or releasing, and fatigue failure of the pattern of the template itself. However, the quality necessary for transferring the pattern cannot be maintained in a series of imprint processes.

<Step S203 to Step S204: Cleaning Conditions and Cleaning>
In the above imprint process, if no measures are taken with regard to the quality of the work template and imprinting is continued, the result is that the semiconductor circuit will not operate normally due to abnormalities in the transferred pattern. End up.

  In order to avoid this problem, with respect to the work template, it is determined whether or not a predetermined number of times of transfer (imprint) has been performed (step S203), and when the number of times has been reached, the work template is cleaned. (Step S204). As a result, the risk of forming a defective pattern due to the above-described foreign matter or template pattern defect is reduced.

<Step S205 to Step S206: Defect Inspection and Discard>
In the defect inspection shown in step S205, it is inspected whether foreign matter is not attached to the work template and whether there is a defect such as a defect in the uneven pattern. If there is no problem as a result of the defect inspection, the work template is used again for imprinting.

  On the other hand, if a fatal defect (such as a crack in the support substrate) is found on the work template as a result of the defect inspection, the work template is discarded (step S206).

  In addition to the defect inspection, the pattern of the template may be reduced by periodically cleaning the work template. Regarding the number of times of cleaning the work template, it is also necessary to manage the dimensions under the conditions of pattern thinning.

  As described above, the work template is a consumable item. In other words, by performing a predetermined cleaning process every number of imprints or every specified number of imprints, pattern thinning occurs, and the dimensions of the original template pattern deviate from the standard and cannot be used as a work template. It becomes a state. At that point, the template is discarded.

  In the pattern formation method according to the reference example, when the work template is washed, it does not fit in the original pattern standard and it is out of the dimension standard, or the work template itself has a missing pattern Can only discard the work template. Discarding the work template is a factor in reducing productivity in pattern formation.

Next, based on FIG. 1, it is a flowchart which illustrates the pattern formation method provided with the template correction method which concerns on this embodiment.
As shown in FIG. 1, the pattern forming method according to the present embodiment includes template production (step S101), replica template production (step S102), imprint (step S103), determination of cleaning conditions (step S104), template. Normal cleaning (step S105), strong template cleaning (step S106), defect inspection (step S107), template correction (step S108), and template destruction (step S109).

<Step S101: Template production>
In the production of the template shown in step S101, a master template and a work template are produced. The production of this template is the same as the production of the template in the reference example shown in step S201 of FIG.

<Step S102: Replica template production>
In the production of the replica template shown in step S102, a replica template is produced from the master template or the work template. The replica template has a pattern (second pattern) in which the unevenness of the work template pattern (first pattern) is inverted.

  In order to manufacture a replica template, for example, a pattern is formed by an imprint method using a work template. For example, a resin agent such as polydimethylsiloxane (PDMS) is applied on a QZ substrate, and a resist is applied thereon. Next, a resist pattern is formed by an imprint method using a work template.

  Next, the resin agent is etched through the resist pattern. As a result, a replica template having a resin agent pattern (an uneven pattern obtained by inverting the uneven shape of the work template) on the QZ substrate is completed.

  In addition, the replica template uses mask data used when the master template is manufactured, performs EB exposure on the EB resist applied on the QZ substrate, forms a pattern, and develops the resist and etches the QZ substrate. You may make it.

<Step S103: Imprint>
In the imprint represented in step S103, the pattern is transferred onto the substrate using the work template in the same manner as the imprint represented in step S202 in FIG.

<Step S104 to Step S106: Cleaning Conditions and Cleaning>
It is determined whether or not a predetermined number of times of transfer (imprint) has been performed using the work template (step S104). S106). Depending on the cleaning conditions, a plurality of stages of cleaning (for example, normal cleaning (step S105) and strong cleaning (step S106)) may be performed.

<Step S107 to Step S109: Defect Inspection, Correction, Discard>
In the defect inspection shown in step S107, it is inspected whether foreign matter has adhered to the work template and whether there is a defect such as a defect in the uneven pattern. If there is no problem as a result of the defect inspection, the work template is used again for imprinting.

  On the other hand, if a fatal defect (such as a crack in the support substrate) is found on the work template as a result of the defect inspection, the work template is discarded (step S109).

  In addition, as a result of defect inspection, there is no fatal defect on the work template, but it cannot be used as a work template because it is out of the original template pattern dimension standard due to pattern thinning or pattern loss. If it is determined that it is in the state, the work template is corrected (step S108).

  According to this embodiment, even if there is pattern thinning or pattern loss of the work template, the work template can be repaired and reused without being discarded. You can continue to use it. As a result, the productivity of pattern formation is greatly improved. Further, pattern thinning and pattern defect correction can be realized by the imprint method, and the quality of the template itself is stabilized.

  Next, a specific example of the work template cleaning method applied in the present embodiment will be described.

  As one of the methods for cleaning the work template, there is an immersion cleaning method called RCA cleaning applied in a semiconductor manufacturing line. In this cleaning method, ammonia hydrogen peroxide solution, hydrochloric acid hydrogen peroxide solution, dilute sulfuric acid, dilute hydrofluoric acid heated to 60 ° C. to 80 ° C., for example, in order to remove particles and organic contamination from the surface of the work template. In this method, the workpiece template is immersed in a chemical such as the above, and after each chemical treatment, the workpiece is rinsed with pure water for about 10 minutes each time to obtain a clean template surface.

  Further, in order to increase the cleaning effect, a bubbling method by ultrasonic cleaning, a brush cleaning method, or the like is incorporated as necessary, and cleaning conditions with little pattern damage are appropriately selected. Further, ozone water and dilute hydrofluoric acid are alternately sprayed on the work template for about 5 seconds to 10 seconds at room temperature, and this is repeated several times to remove particles and various organic impurities on the template surface with high efficiency. There are also methods.

  In any of the cleaning methods, when the cleaning solution is increased by increasing the chemical concentration, damage to the pattern of the work template (mainly pattern thinning) tends to become severe.

  In the present embodiment, in the cleaning process of the work template, normal cleaning (step S105) in which foreign matter can be removed under conditions where damage to the pattern is small, and normal cleaning (step S105) is given priority to the cleaning capability by increasing the chemical concentration or the like. In step S105, strong cleaning (step S106) is selected according to the cleaning condition (step S104) to remove dirt (for example, foreign matter sandwiched between patterns or stuck foreign matter) from the pattern surface that cannot be removed in step S105.

  As cleaning conditions (step S104) at this time, (1) when pattern damage due to repeated cleaning reaches a limit, specifically, immediately before the pattern width becomes out of specification due to pattern thinning, (2) normal cleaning If there is a foreign material that cannot be removed,

  In the present embodiment, the above two cases (1) and (2) are given as specific examples, but other examples may be used. For example, there is a case where a case where it is desired to perform strong cleaning suddenly occurs. In the flowchart shown in FIG. 2, the above-described cleaning conditions and cleaning methods are shown in steps S104 to S105, but various cleaning methods can be combined in addition to normal cleaning (step S105) and strong cleaning (step S106). You may make it process.

  Thus, after carrying out the strong cleaning, the work template itself is inspected, and after confirming that there is no non-removable foreign matter other than pattern defects on the template, the work template repair processing shown in step S108 is performed. . Thereby, a pattern is formed again on the work template based on the replica template. As a result, a work template having a quality equivalent to the quality of the initial work template is reproduced.

  Next, a specific example of the work template cleaning conditions applied in the present embodiment will be described.

  According to the above-described strong cleaning, it can be seen that damage of about 1 nm on one side (2 nm on both sides) occurs with respect to the center of the pattern as a thin value of the pattern dimension of the template. After the cleaning process, if the CD (Critical Dimension) of the work template pattern is within the standard, the process proceeds to the normal imprint (step S103). If the CD is out of the standard, the imprint using the replica template is performed. Play the work template by the law. The quality of the reproduced work template is equivalent to the quality of the replica template, and the pattern dimension also returns to the initial dimension value.

Next, a description will be given of the compensation material used when the work template is corrected.
It is important to select an optimum material as a compensation material used for correcting the work template in consideration of transferability for each pattern to be transferred.

  In this embodiment, at least one selected from polymer materials such as PDMS, perfluoropolyether (PFPE), glass material, and metal material is used as the filling material. Patterns modified with these materials have sufficient strength and mass productivity.

  It should be noted that the strength of the modified work template is inferior to that of a template based on a QZ material, in which a base material and an uneven pattern are integrally formed. However, since the current imprint method requires cleaning depending on the number of imprints, if the pattern can withstand the required cleaning, use the work template correction method of the present embodiment described above. It is possible to revive and recycle the template many times. Therefore, there is no practical problem even if it is not an integrated template of the base material and the concavo-convex pattern made of the QZ material.

  The merit by the modification of the work template is very large compared to the method of exchanging the work template every time it is used. That is, by modifying and using the work template, the quality of the concave and convex pattern of the work template is maintained, the quality of the pattern transferred by the imprint method is stabilized, the productivity is improved, and the quality is controlled. In addition, the benefits are extremely large.

  An advantage of the imprint method is that it does not require expensive optics, advanced illumination sources or special resist materials that are often required in normal optical lithography processes. Most of the cost in the imprint method is a production cost of the template. Since the work template can be reproduced and used repeatedly as in the present embodiment, a significant cost reduction in pattern formation by the imprint method is achieved.

Next, a specific example of a work template correction method applied in the present embodiment will be described.
3A to 3C are schematic cross-sectional views illustrating a work template correction method (part 1).
3A to 3C illustrate a method of correcting the work template 110 in which a part of the convex pattern 11 is missing.

  First, as shown in FIG. 3A, the filling material 30 is applied to the replica template 210. PDMS is used as the filling material 30. When the pattern to be corrected extends over the entire work template 110, the compensation material 30 is applied to the entire replica template 210.

  On the other hand, when the pattern to be corrected is a part of the work template 110, the supplementary material 30 may be applied to a portion of the replica template 210 corresponding to a portion where the work template 110 needs to be corrected.

  In this case, when the coordinates where the defect exists are known from the inspection result of the apparatus for inspecting the defect of the work template 110, the compensation material 30 is applied based on the information of the coordinate.

  Further, a resist (for example, a dummy resist mainly composed of a volatile component) having little influence on the imprint method may be applied to a portion where the work template 110 is not required to be corrected. By applying the compensation material 30 and the dummy resist for correction, when the work template 110 is brought into contact with the compensation material 30 and the dummy resist, the difference in the adsorption force between the templates due to the capillary principle is suppressed, Tilt between both templates is prevented.

  Next, as illustrated in FIG. 3B, the work template 110 is overlaid on the replica template 210, and the filling material 30 applied to the replica template 210 is brought into contact with the work template 110. At this time, the concave pattern 21 of the replica template 210 and the convex pattern 11 of the work template 110 mesh with each other, and the filling material 30 enters between them.

  The inner dimension of the concave pattern 21 of the replica template 210 is slightly larger than the outer dimension of the convex pattern 11 of the work template 110. This takes into account the shrinkage when the filling material 30 is cured.

  The convex pattern 11 of the work template 110 is slightly narrowed even within the CD standard by repeating imprinting and cleaning. For this reason, when reproducing the pattern using the replica template 210, if the filling material 30 is previously attached to the convex pattern 11, the convex pattern 11 having an appropriate size is reproduced in a contracted state after curing.

  Next, the filling material 30 is irradiated with light, for example, in a state where the work template 110 is in contact with the filling material 30 applied to the replica template 210 and cured. Thereafter, as shown in FIG. 3C, the work template 110 is released from the replica template 210. Thereby, the correction of the work template 110 is completed.

  In the workpiece template 110 after correction, the correction pattern 11A is added to the missing portion, and the correction portion 11B made of the filling material 30 is replenished around the thin convex pattern 11. That is, the corrected work template 110 includes a base material 10 and a plurality of convex patterns 11, and at least one of the plurality of convex patterns 11 includes a correction pattern 11 </ b> A made of a material different from that of the base material 10.

  In such a method of correcting the work template 110 by correcting the partial pattern, it is possible to omit the pattern formation by the entire imprint method by not considering an extra pattern in the imprint method. As a result, it is possible to avoid as much as possible the effects of preventing both the templates themselves from being smudged during imprinting and the damage to both templates due to the imprinting.

  Further, even if pattern loss and pattern thinning occur at the same time, the pattern dimension of the work template 110 can be restored by a single correction process using the imprint method.

  In the work template 110, a portion where the pattern defect is likely to occur (uneven pattern) may be formed in advance by the filling material 30. In this case, the productivity is further improved by incorporating the pattern correction with the filling material 30 by the imprint method after cleaning the work template 110.

  Further, in the work template correction method (part 1), the replica template 210 used here is generally manufactured in the same pattern as the work template 110 to be corrected, with the concave and convex portions reversed. For example, with respect to the replica template 210, a plurality of sub-replica templates (small replica templates) in which irregularities of only an arbitrary correction pattern are formed may be manufactured.

  As a specific example, as a concavo-convex pattern formed on the sub-replica template, only a part of the pattern on the work template 110 (for example, a circuit block (see attached sheet) or a memory cell portion) is formed) It only has to be done.

  Furthermore, since the correction part of the work template 110 is likely to occur at an arbitrary position, an arbitrary pattern, or an arbitrary pattern block, the occurrence frequency of the correction part is simulated in advance based on the generation results and the generation mechanism. For example, it may be assumed. For example, sub-replica templates are prepared for each of a plurality of correction units having a high frequency according to the assumed occurrence frequency. Thereby, the lifetime of the replica template itself can be extended.

  For example, in a product such as a semiconductor memory, cell blocks having the same pattern are repeated. Therefore, a sub replica template corresponding to the cell block pattern is formed. In pattern formation of a semiconductor memory, the occurrence frequency of pattern defects in cell blocks is high.

  Therefore, a sub replica template is prepared for the cell block, and the replica template is formed, so that the sub replica template is applied to a portion having a high pattern defect frequency. The same type of sub-replica template is applied to other cell blocks. As a result, the life of the replica template itself can be extended by exchanging only the sub-replica template having the same pattern shape.

  Moreover, even if an inexpensive material such as a resinous material is used instead of an expensive QZ substrate, the overall productivity is improved by sufficiently meeting the production cost.

  Here, an example of a method for creating a sub replica template will be described. In this example, a method of creating a replica template from a template (mother template) that is an original plate when manufacturing the work template 110 is taken as an example.

(First method)
The first method is a method of creating a sub replica template by dividing one replica template 210. That is, one replica template 210 is configured by combining a plurality of sub-replica templates.

As an example, a sub replica template is created for each block in the circuit design.
FIGS. 4A and 4B are diagrams illustrating an example in which a sub replica template is formed for each block.
As shown in FIG. 4A, circuit data in circuit design has a hierarchical structure of circuit blocks. For example, each circuit data of design-A to design-N has a hierarchical structure having a plurality of circuit blocks (also referred to as circuit modules). The sub replica template is manufactured for each circuit block.

Then, when a predetermined circuit block is applied in circuit design, a sub replica template corresponding to the applied circuit block is prepared. By combining the sub-replica templates, one replica template corresponding to the designed circuit is configured as shown in FIG. 4B.
In this way, if a sub-replica template is prepared for each circuit block, when designing a circuit by applying a circuit block of an arbitrary hierarchy, it is only necessary to select a sub-replica template corresponding to the applied circuit block. A replica template 210 corresponding to the designed circuit is easily prepared.

(Second method)
The second method is a method of creating a sub replica template using a mother template in which a unique circuit pattern is arranged.
FIG. 5 is a schematic view illustrating a mother template in which a pattern area is divided.
In the mother template 100, the pattern region R is arranged as a unique circuit pattern so as to be easily divided.

  In the second method, such a mother template 100 is used to create a replica template 210, and the replica template 210 is cut into regions R that are arranged so that the mother template 100 can be easily divided.

  Note that individual sub-replica templates may be formed for the region R of the mother template 100 arranged so as to be easily divided. The sub replica template may be prepared uniformly for all the regions R, or for example, only the sub replica template corresponding to the region R of a specific pattern having a high correction frequency may be prepared. Also, a larger number of sub-replica templates corresponding to the region R having a high correction frequency may be prepared as compared with the region R having a low correction frequency.

  For example, in a product such as a semiconductor memory, cells having the same shape occupy 90% or more of the entire pattern. In this case, one sub-replica template may be formed for the region R having the same pattern shape.

  That is, since the cell block pattern which is one unit of the pattern is repeated, the minimum block pattern is set as the sub replica template. As a result, one replica template is created from one mother template 100, and then the cell block that needs to be modified is first created by combining the sub-replica templates formed in the smallest unit. The same thing as a replica template can be configured easily.

  Further, by setting the sub replica template as the minimum unit of the repeating pattern, it is possible to divide one replica template and create tens or hundreds of sub replica templates at a time.

  Furthermore, a unit of IP (Intellectual Property) core in circuit design, a unit composed of a plurality of IP cores, a unit of pattern across the design data hierarchy (see FIG. 4A), a different product (for example, a semiconductor) A replica template may be created in units of patterns common to (memory). As a result, replica templates corresponding to patterns used for all design hierarchies can be created at a time.

6A to 6C are schematic cross-sectional views illustrating a work template correction method (part 2).
6A to 6D illustrate a method for correcting a work template in which pattern thinning has occurred.

  6A shows a work template 110 having a convex pattern 11 before pattern thinning occurs, and FIG. 6B shows a work template 110 having a convex pattern 11 ′ with pattern thinning produced. It is shown. For example, when pattern thinning occurs by performing strong cleaning a plurality of times, the entire pattern is corrected by the following procedure.

  First, as shown in FIG. 6C, the compensation material 30 is applied to the work template 110 in which the pattern is thinned. For example, PDMS is used for the filling material 30.

  Next, as illustrated in FIG. 6D, the replica template 210 is overlaid on the work template 110, and the replica template 210 and the filling material 30 are brought into contact with each other. Thereby, the convex pattern 11 ′ of the work template 110 and the concave pattern 21 of the replica template 210 mesh with each other, and the gap between them is filled with the filling material 30.

  The inner dimension of the concave pattern 21 of the replica template 210 is slightly larger than the outer dimension of the target convex pattern 11 in consideration of shrinkage when the filling material 30 is cured.

  Next, in a state where the replica template 210 is in contact with the filling material 30 applied to the work template 110, the filling material 30 is irradiated with light, for example, and cured.

  Thereafter, as shown in FIG. 6E, the replica template 210 is released from the work template 110. Thereby, the correction of the work template 110 is completed.

  In the work template 110 after correction, the filling material 30 is provided so as to cover the periphery of the convex pattern 11 ′ that is thinned. That is, the corrected work template 110 includes the base material 10 and the convex pattern 11, and the convex pattern 11 is provided around the central portion 11 </ b> C and the central portion 11 </ b> C. 10 and a correction portion 11B formed of a different material.

  In such a corrected template for work, since the periphery of the center portion 11C is covered with the correction material 11B by the filling material 30, the correction portion 11B functions as a protective film. Thereby, the damage of the convex pattern 11 is suppressed by the imprint method using the work template 110 after correction.

  In the above-described method for correcting the work template 110, the replica template can be removed even if the pattern is damaged by strong cleaning such as strong acid cleaning without removing the sticking-off foreign matter. By 210, the work template 110 having the original pattern size can be reproduced again.

  In general acid cleaning, pattern damage of about 1 nm on one side (2 nm on both sides) with respect to the center of the convex pattern 11 of the work template 110 is generally performed. However, the cleaning concentration is increased to 2 nm on one side (4 nm on both sides). By setting the cleaning conditions to a degree of pattern damage, almost all foreign matters are removed, including pinching and sticking foreign matter that could only be removed by a method such as physically scraping with a brush or the like.

  In this embodiment, it is possible to use cleaning with enhanced cleaning performance such as thickening cleaning chemicals, and foreign matter stuck to the surface of the pattern or pinched (screwed) between patterns when imprinting between templates It is not necessary to scrape the defect by a mechanical method (for example, brush scrub method). Thereby, physical damage to the pattern can be reliably eliminated, and the cleaning efficiency can be increased.

  In addition, when the liquid concentration of the chemical cleaning is plotted on the horizontal axis and the cleaning efficiency (the number of removed foreign substances attached or sandwiched between the patterns) is plotted on the vertical axis, the acid cleaning concentration is high when the variation amount of the pattern dimension is experimentally expressed. It is generally known that the larger the pattern dimension variation is, the higher the acid cleaning concentration is, the higher the number of removed foreign matters (removal efficiency) is.

  In the present embodiment, an optimal chemical cleaning concentration and cleaning conditions (processing time, etc.) are determined for each pattern of the work template 110, an arbitrary replica template 210 is selected according to the variation amount of the pattern dimension, and the imprint method is used. The pattern of the work template 110 is corrected. Thereby, an optimal template correction method is provided.

  In the present embodiment, the optimum foreign matter removal method is determined by combining the concentration of chemical solution for normal cleaning and strong cleaning, the processing time, and, if necessary, brush scrub cleaning as cleaning conditions. The cleaning conditions are not limited to two, and various cleaning conditions are selected according to the pattern characteristics.

  In addition, template cleaning conditions such as template stains and defects that are likely to become defective in the number of times of imprinting are set in advance, and powerful cleaning is performed as needed during regular cleaning or when the occurrence of defects is clarified. It is more desirable to switch to

In the above-described method for correcting the work template 110, the concave pattern 21 of the replica template 210 may be provided with a taper angle.
7A and 7B are schematic cross-sectional views illustrating the shape of the concave pattern.
7A and 7B are schematic cross-sectional views in which a portion of one concave pattern 21 of the replica template 210 is enlarged.

  In the concave pattern 21 shown in FIG. 7A, a linear tapered portion 21A is provided in the vicinity of the opening. In the concave pattern 21 shown in FIG. 7B, a curved tapered portion 21B is provided in the vicinity of the opening. By providing the tapered portions 21A and 21B, the opening width of the concave pattern 21 becomes wider from the bottom toward the opening end.

  In this way, by providing the concave portions 21 of the replica template 210 with the tapered portions 21A and 21B, when the work template 110 is corrected, the work template 110 is superimposed on the replica template 210, and the work template 110 When the convex pattern 11 ′ is inserted into the concave pattern 21 of the replica template 210, the convex pattern 11 ′ is called into the concave pattern 21 along the tapered portions 21A and 21B.

  When the work template 110 is corrected, the filling material 30 is applied to the replica template 210, and the work template 110 is overlaid thereon. At this time, even if there is a slight misalignment between the replica template 210 and the work template 110, the taper portions 21A and 21B of the concave pattern 21 of the replica template 210 when the work template 110 is imprinted on the replica template 210. Serves as a guide, and the convex pattern 11 ′ of the work template 110 is accurately aligned within the concave pattern 21 of the replica template 210.

  When such tapered portions 21A and 21B are provided, the filling material 30 is filled between the tapered portions 21A and 21B and the work template 110, and an extra pattern is formed. However, this portion is not used in imprinting using the work template 110 and does not affect pattern formation.

  In the specific method for correcting the work template 110 described above, the replica template 210 may be formed of a material different from the material of the work template 110. For example, a material softer than the work template 110 (for example, PDMS) is applied to the replica template 210. On the other hand, the work template 110 is used for imprinting on a semiconductor wafer or the like. Therefore, the QZ material is applied to the work template 110.

  As described above, since the materials of both the replica template 210 and the work template 110 are different, even when the replica template 210 and the work template 110 come into contact with each other when the work template 110 is modified, Frictional force is reduced and mechanical damage is reduced. As a result, the life of the replica template 210 is extended.

  As a material of the replica template 210, it is desirable to use one selected from PDMS, PFPE, and a plurality of glass materials in order to avoid the disadvantage of being easily damaged when biting dust.

  Further, as the replica template 210, a plurality of replica templates 210 may be prepared by dividing a portion that is not strict as a correction accuracy and a portion that is strict. As a result, a plurality of replica templates 210 are selectively used as necessary, and a portion that needs to be corrected is partially (selectively) corrected by the imprint method. By doing so, since the damage to extra portions is reduced, the risk of increased defects can be reduced.

  The replica template 210 may be provided corresponding to a partial area of the work template 110. That is, the pattern area of one work template 110 may be divided into a plurality of blocks, and a sub replica template may be prepared for each block.

  Further, one replica template 210 may be configured by combining a plurality of sub-replica templates. For example, in the case of a product such as a semiconductor memory, 90% or more of the entire pattern region is a repetition of the same pattern shape constituting the memory pattern. Therefore, a plurality of sub-replica templates having the same concave pattern 21 shape may be prepared, and these sub-replica templates may be combined into one replica template 210.

  There are various possible combinations of sub-replica templates. For example, in the case of memory patterns, sub-replica templates can be divided into small groups for each memory circuit collective pattern called cell block and each IP core used in circuit design. prepare. Further, a sub replica template necessary for correction may be automatically selected from information on the defect position of the work template 110 (position, defect shape, etc.).

  When the replica template 210 is manufactured, it is preferable to manufacture it based on the quality of the master template. For example, the quality of the replica template 210 manufactured based on one master template may differ from the quality of the replica template 210 manufactured from another master template.

  In order to avoid such a change in the conditions for correcting the work template 110 from the replica template 210 due to the difference in the master template, the quality of the master template serving as a reference in manufacturing the replica template 210 is guaranteed. It is desirable to select the one that is. As a result, it is possible to absorb quality variation components such as a CD variation difference for each master template and an overall CD average value difference.

  In addition, when a pattern is formed by the imprint method, the work template 110 is cleaned by the number of imprints and the pattern is corrected by the imprint method for a portion where the pattern defect of the work template 110 is likely to occur. It is desirable to do.

  Further, the occurrence rate of the pattern defect or the like at the position of the work template 110 is verified by the material of the work template 110 and the material of the compensation material 30 for correction, and this is reflected in the correction of the work template 110. Also good.

  Further, the tendency of the number of normal cleanings and the number of strong cleanings may be converted into table data in advance, and the CD may be guaranteed by grasping the number of cleanings.

  Note that, even when the work template 110 has no defects, strong cleaning may be incorporated according to a series of imprints using the work template 110. After the strong cleaning, when the CD of the concave / convex pattern of the work template 110 is out of the standard, the CD of the pattern size is also restored by regenerating the work template 110 using the replica template 210.

  Specifically, the tendency of pattern thinning due to normal cleaning and strong cleaning is tabulated in advance, and the amount of CD variation (CD thinning amount) for each template is grasped while calculating the number of normal cleaning times and the number of strong cleaning times. By calculating, the CD of the template is guaranteed or the work template 110 is restored if necessary.

  Thereby, since the work template 110 can be restored and reused, the quality of the work template 110 can be maintained for a long period of time, the production cost can be reduced, and a constant quality can be maintained. It becomes like this.

(Example)
Next, an example of a method for correcting the work template 110 will be described.
The width of the convex pattern 11 of the work template 110 is about 15 nm. When the replica template 210 is manufactured from the work template 110, the width of the concave pattern 21 of the replica template 210 is about 3 nm to 6 nm larger than the width of the convex pattern 11 of the work template 110. The difference between the width of the concave pattern 21 of the replica template 210 and the width of the convex pattern 11 of the work template 110 is referred to as a “pattern conversion difference”. In the embodiment, the case where the pattern conversion difference is 6 nm is taken as an example.

Various conditions for correcting the work template 110 are as follows.
(1) The pattern conversion difference is 6 nm.
(2) As a cleaning condition, for example, when importance is attached to the risk of defect occurrence, cleaning is performed once per 1000 imprints. If the risk of defect occurrence is not emphasized, cleaning may be performed once for a larger number of imprints (for example, 2500).
A pattern is formed by the imprint method using the work template 110 under the above conditions (1) and (2).

Pattern thinning by cleaning is as follows.
(3) The CD variation amount for one normal washing is −1 nm.
(4) The CD fluctuation amount for one powerful washing is −3 nm.

The CD standard of the template is as follows.
(5) The template CD standard is ± 5 nm with respect to the width of the convex pattern of 15 nm (if the width of the convex pattern falls below 10 nm, the template is defective). It is assumed that the width of the convex pattern is finished at 15 nm with the CD value of the template as the center value.

  Assuming that no pattern defect occurs under the above cleaning conditions, considering only the thinning of the pattern, for example, normal cleaning is performed once every 2500 imprints (1 lot: equivalent to 25 wafers). In such a case, in order to guarantee the CD, it is judged that the template is defective after the normal number of cleanings is five. Therefore, one work template 110 in 5 lots is calculated to be defective due to a thin pattern.

  In the pattern formation method according to the reference example, the template is discarded after being washed 5 times (the convex pattern width 15 nm becomes 10 nm, which is out of the standard). In this embodiment, strong washing is performed in the final 5th washing step. To do.

  Here, the CD value is 8 nm outside the standard and should be regarded as defective, and the convex pattern 11 ′ of the work template 110 is corrected by the imprint method using the replica template 210 prepared in advance. As a result, in the work template 110, in addition to the convex pattern 11 ′ of the initial QZ material, the correction pattern 11A using the compensation material 30 or the convex pattern 11 (here, the pattern narrowing) including the correction part 11B supplemented with the CD thinning. By including a portion supplemented with the filling material 30 around the 7 nm-width QZ pattern, a pattern equivalent to the initial template in shape can be created.

  Specifically, the width of the concave pattern 21 of the replica template 210 prepared in advance is 21 nm. In the work template 110, the width of the convex pattern 11 'thinned by the cleaning becomes defective at 8 nm. In this state, the filling material 30 is applied on the replica template 210, and the work template 110 is imprinted.

  After that, for example, UV (ultraviolet) light for curing the filling material 30 is irradiated and then released to form the convex pattern 11 in which the correction portion 11B is provided around the convex pattern 11 ′ (central portion 11C). The By doing so, a restoration template having the convex pattern 11 having the same width as the width 15 nm of the convex pattern 11 of the initial work template is completed on the QZ material of the work template 110.

  By using the method for correcting the work template 110 as described above, a pattern that has been thinned in the cleaning process and does not satisfy the standard is restored to a size equivalent to that of the initial work template 110. . This makes it possible to continue using one work template 110 for a long period of time.

  In the embodiment as described above, in the present embodiment, the quality required for the original template is out of the standard, such as pattern thinning due to periodic cleaning of the work template 110, or a pattern defect caused by a pattern defect or the like. Even if such a problem occurs, the template can be restored and used without discarding the work template 110.

  Further, in the present embodiment, with respect to the pattern correction of the template for imprinting, a replica template corresponding to the template is prepared in advance, and the template pattern can be corrected periodically using this replica template. As a result, it is possible to realize the repair of the thin pattern of the template and the correction of the pattern defect by the imprint method. By applying such template pattern correction, the quality of the template itself can be stabilized. Further, by correcting the template by the imprint method, the template can be used for a long time. As a result, productivity in pattern formation is greatly improved.

  As described above, according to the pattern forming method according to the embodiment, a highly accurate template can be reused.

  In addition, although this Embodiment and its modification were demonstrated above, this invention is not limited to these examples. For example, those in which the person skilled in the art appropriately added, deleted, or changed the design of the above-described embodiments or modifications thereof, or combinations of the features of each embodiment as appropriate As long as the gist of the invention is provided, it falls within the scope of the present invention.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 10 ... Base material, 11 ... Convex pattern, 11A ... Correction pattern, 11B ... Correction part, 11C ... Center part, 21 ... Concave pattern, 21A, 21B ... Tapered part, 30 ... Supplementary material, 110 ... Template for work, 210 ... Replica template

Claims (13)

A pattern forming method for forming a pattern using a first template having a first pattern having at least one of a concave portion and a convex portion,
Applying a resin on a substrate, transferring the shape of the first pattern of the first template to the resin, and forming a transfer pattern on the substrate;
Cleaning the first template;
Inspecting the first template;
As a result of the inspection of the first template, when a preset condition is satisfied, the process returns to the step of forming the transfer pattern, and when the condition is not satisfied, the first pattern in which the unevenness of the first pattern is inverted is returned. Modifying the first pattern of the first template with a filling material using a second template having two patterns;
With
The filling material is at least one selected from a resin material, a glass material, and a metal material,
The first pattern has a convex portion,
The second pattern has a recess,
The width of the concave portion is wider than the width of the convex portion,
The step of modifying the first pattern includes applying the filling material onto the second template, superimposing the second template and the first template through the filling material, and arranging the second pattern and the first template. A pattern forming method including filling and filling the filling material between one pattern and forming a correction portion by the filling material on the first template side. A pattern forming method for forming a pattern using a first template having a first pattern having at least one of a concave portion and a convex portion,
Applying a resin on a substrate, transferring the shape of the first pattern of the first template to the resin, and forming a transfer pattern on the substrate;
Cleaning the first template;
Inspecting the first template;
As a result of the inspection of the first template, when a preset condition is satisfied, the process returns to the step of forming the transfer pattern, and when the condition is not satisfied, the first pattern in which the unevenness of the first pattern is inverted is returned. Modifying the first pattern of the first template with a filling material using a second template having two patterns;
A pattern forming method comprising:   The step of correcting the first pattern includes filling and hardening the filling material between the second pattern and the first pattern, and forming a correction portion by the filling material on the first template side. The pattern formation method of Claim 2 containing.   The step of modifying the first pattern includes applying the filling material on the second template, and superimposing the second template and the first template through the filling material. The pattern formation method as described.   The pattern forming method according to claim 2, wherein the filling material is at least one selected from a resin material, a glass material, and a metal material. The first pattern has a convex portion,
The second pattern has a recess,
The width of the said recessed part is a pattern formation method as described in any one of Claims 2-5 wider than the width | variety of the said convex part.   The step of correcting the first pattern includes applying the compensation material to a portion of the second pattern for correcting the first pattern determined to be defective based on a result of inspection of the first template. Item 7. The pattern forming method according to any one of Items 2 to 6. The step of inspecting the first template includes obtaining information of coordinates of a defective portion of the first template,
The pattern according to any one of claims 2 to 7, wherein the step of correcting the first pattern includes applying the filling material to a portion of the second pattern using information on coordinates of the defective portion. Forming method.   3. The step of cleaning the first template includes performing a determination to clean the first template when the number of times of forming the transfer pattern by the first template exceeds a predetermined number. The pattern formation method as described in any one of -8.   The step of cleaning the first template includes performing a determination to clean the first template when a dimension of the first pattern reaches a predetermined dimension. The pattern formation method as described in one.   The step of cleaning the first template includes selecting one of cleaning based on a first cleaning condition and cleaning based on a second cleaning condition having a stronger cleaning power than the first cleaning condition. The pattern formation method as described in any one of Claims 2-10.   The pattern formation method according to claim 11, wherein the cleaning under the second cleaning condition is a cleaning using a chemical that narrows the width of the convex portion included in the first pattern.   The step of cleaning the first template includes the step of cleaning the first template with the second cleaning condition when foreign matter adhering to the first template has not been removed after the cleaning with the first cleaning condition. The pattern formation method of Claim 11 or 12 including performing washing | cleaning by.

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