Embodiments described herein relate generally to a template, a manufacturing method of the template, and a position measuring method in the template.
In a technique of manufacturing a semiconductor device including various kinds of many semiconductor elements such as transistors, a pattern scaling technique for increasing a degree of integration has been used. For further scaling, it is a critical issue to improve the accuracy of overlapping between layers. For this reason, a technique for improving management of a pattern position accuracy of a photomask or a nanoimprint template which is a factor of a variation has been developed.
Examples of a method of performing management of the position accuracy of a photomask includes (1) a method of directly measuring a device pattern and (2) a method of measuring a measurement pattern that does not function as a device. Meanwhile, in the optical lithography, a pattern on a photomask is transferred to a substrate at ¼ times, whereas in the nanoimprint lithography, a pattern on a photomask is transferred to a substrate at the same size, a device pattern has the size of a position measurement limit or less (the size of 80 nm or less). For this reason, there is a problem in that it is difficult to perform position measurement through a pattern position measuring device.
Further, when a measurement pattern is arranged, in a device having a high degree of integration in a chip such as memory devices, when the measurement pattern is transferred to the substrate, a problem occurs in a device operation. For this reason, the measurement pattern is arranged in a region (kerf) outside a chip. Thus, there is a problem in that under this condition, it is difficult to measure the position in a chip, the number of measurement patterns arranged in a template is restricted, and it is difficult to perform multi-point measurement.
In general, according to one embodiment, provided is a template in which a transfer region on which a first pattern to be transferred to a processing target is arranged and a non-transfer region surrounding the transfer region are formed on a principal surface of a template substrate. The template includes a second pattern used to measure deviation of a pattern formed on the template substrate from a design position in at least the transfer region. The second pattern arranged on the transfer region is not transferred to the processing target when a transfer to the processing target is performed through an imprint material.
Hereinafter, a template, a manufacturing method of the template, and a position measuring method in the template according to exemplary embodiments will be described in detail with reference to the accompanying drawings. The present invention is not limited these exemplary embodiments.
As will be described below, in the template according to the first embodiment, deviation is measured using a measurement pattern 22 in the process of manufacturing the template illustrated in
The non-completed template 10A has a structure in which a plurality of transfer regions 12 are defined on a template substrate 11 made of quartz or the like as illustrated in
The non-completed template 10A includes a plurality of patterns 22 used to measure a degree by which a pattern actually formed on the template substrate 11 is deviated on design data of a template. In the first embodiment, the measurement pattern 22 is formed not only the kerf 13 but also the transfer region 12 as in a general template. The measurement pattern 22 has a concave shape caved into the template substrate 11. For example, the measurement pattern 22 has a cross shape and has the size of 80 nm or more that can be measured (optically recognized) by a pattern position measuring device. For example, as the measurement pattern 22, illustrated is a cross pattern in which two rectangular patterns having the length of 1 μm and the width of 300 nm change their directions at 90° in the plane of the template substrate 11 and intersect with each other near the center of each other. In this example, the device pattern 21 has the size of 50 nm. In the transfer region 12, the measurement pattern 22 is formed on a region in which the device pattern 21 is not arranged.
The non-completed template 10A illustrated in
As illustrated in
The embedded layer 23 is not particularly limited. For example, as the embedded layer 23, a layer having the same refractive index as the template substrate 11 may be used, and a layer having a different refractive index from the template substrate 11 may be used. When the layer having the same refractive index as the template substrate 11 is embedded, it is difficult (hard) to optically recognize the measurement pattern 22 in the completed template 10B. Meanwhile, when the layer having the different refractive index from the template substrate 11 is embedded, the measurement pattern 22 can be recognized even in the completed template 10B. When an optically recognizable material is used as described above, the embedded layer 23 embedded in the measurement pattern 22 can be used as a strain measurement pattern used to measure strain accumulated on the completed template 10B.
Next, the template manufacturing method will be described.
First of all, a mask layer 51 is formed on a principal surface of the template substrate 11 as illustrated in
Thereafter, a resist pattern 52a used to form the device pattern 21 and the measurement pattern 22 is formed by light exposure and development using an electron beam lithography device as illustrated in
Then, the mask layer 51 is etched by dry etching using the resist pattern 52a as a mask, and thus the device pattern 21 and the measurement pattern 22 are transferred to the mask layer 51 as illustrated in
Thereafter, the template substrate 11 is etched up to a predetermined depth by dry etching using the patterned mask layer 51 as a mask as illustrated in
Then, positional deviation from the design data is measured using the measurement pattern 22, that is, the measurement pattern 22 of the template substrate 11, through a pattern position measuring device (step S16). Then, it is determined whether or not the positional deviation is within an allowable range having on influence on a characteristic of a product to be manufactured even when a subsequent process is continued using the corresponding template (step S17).
When it is determined that the positional deviation is within the allowable range (Yes in step S17), the embedded layer 23 is embedded in the measurement pattern 22 with the concave structure in the transfer region 12 as illustrated in
Thereafter, the completed template 10B is used for manufacturing of a semiconductor device or manufacturing of a daughter template. Specifically, a processing target which is a wafer on which a semiconductor device is to be manufactured or a daughter template is coated with a hardening resin (an imprint material) curable by light (ultraviolet (UV) light or the like) or heat, and the completed template 10B is pressed into the processing target while irradiating light or applying heat, and thus the hardening resin is cured. Thereafter, the completed template 10B is removed, and a process of processing (etching) the processing target using the cured hardening resin as a mask is performed.
However, when it is determined in step S17 that the positional deviation is not within the allowable range (No in step S17), it is difficult to use the template as a product, and thus the template is discarded (step S19), and the template manufacturing process ends.
In the first embodiment, when the template is manufactured, the concave-shaped measurement pattern 22 is formed not only on the kerf 13 but also on the transfer region 12, the positional deviation of the design position of the pattern is measured using the measurement pattern 22, and then concave-shaped measurement pattern 22 is filled. Thus, compared to the example in which the measurement pattern 22 is arranged only on the kerf 13, measurement points of the positional deviation are increased, and thus there is an effect by which the template can be manufactured with a high degree of accuracy. Further, since the measurement pattern 22 formed on the transfer region 12 is filled, when a device is actually manufactured, the measurement pattern 22 is not transferred onto the processing target. Consequently, there is an effect by which the template can be manufactured with a high degree of accuracy without affecting a device.
In addition, as the measurement pattern 22 of the transfer region 12 is filled with the embedded layer 23 which is optically recognizable in the template, there is an effect by which when a product is manufactured using the template, the measurement patterns 22 on the kerf 13 and the transfer region 12 can be used for measurement of strain or the like accumulated in the template.
In the second embodiment, similarly to the first embodiment, the non-completed template 10A includes the measurement patterns 22 on the kerf 13 and the transfer region 12, and the completed template 10B includes the measurement pattern 22 only on the kerf 13, and the measurement pattern 22 on the transfer region 12 is removed.
In the second embodiment, the device pattern 21 and the measurement pattern 22 have the convex shape as illustrated in
Next, the template manufacturing method will be described.
First of all, a mask layer 51 is formed on a principal surface of the template substrate 11 as illustrated in
Thereafter, a resist pattern 52a used to form the device pattern 21 and the measurement pattern 22 is formed by light exposure and development using an electron beam lithography device as illustrated in
Then, the mask layer 51 is etched by dry etching using the resist pattern 52a as a mask, and thus the device pattern 21 and the measurement pattern 22 are transferred to the mask layer 51 as illustrated in
Thereafter, the template substrate 11 is etched up to a predetermined depth by dry etching using the patterned mask layer 51 as a mask as illustrated in
Then, positional deviation from the design data is measured using the measurement pattern 22, that is, the measurement pattern 22 of the template substrate 11, through a pattern position measuring device (step S36). Then, it is determined whether or not the positional deviation is within an allowable range having on influence on a characteristic of a product to be manufactured even when a subsequent process is continued using the corresponding template (step S37).
When it is determined that the positional deviation is within the allowable range (Yes in step S37), the measurement pattern 22 in the transfer region 12 is removed as illustrated in
However, when it is determined in step S37 that the positional deviation is not within the allowable range (No in step S37), it is difficult to use the template as a product, and thus the template is discarded (step S39), and the template manufacturing process ends.
In the second embodiment, the template is formed such that the device pattern 21 and the measurement pattern 22 have the convex structure, and the measurement pattern 22 is formed on both the kerf 13 and the transfer region 12. Further, after positional deviation measurement using the measurement pattern 22 ends, the measurement pattern 22 on the transfer region 12 is removed by etching, and a semiconductor device is manufactured using the template. Thus, there is an effect by which when the template is manufactured, the positional deviation of the pattern formed on the template can be precisely measured using many measurement patterns 22. In addition, there is an effect by which when a semiconductor device is manufactured, since the measurement pattern 22 is not present on the transfer region 12, a device characteristic is not adversely affected.
In the third embodiment, the device pattern 21 of the transfer region 12 is a pattern of a line-and-space form. The device pattern 21 and the measurement pattern 22 have a convex shape as illustrated in
Further, the measurement pattern 22 is patterned into a pattern of a cross shape described in the first embodiment or the second embodiment using the line-and-space pattern. In other words, the non-completed template 10A has the structure in which the measurement pattern 22 is embedded (overlaps) in the line-and-space pattern.
When the positional deviation measurement in the non-completed template 10A ends, the measurement pattern 22 on the transfer region 12 is removed by etching. In other words, the pattern embedded between the line patterns 211 is removed. Consequently, as illustrated in
The template manufacturing method is basically similar to the second embodiment except the process of removing the measurement pattern 22. In this regard, the process of removing the measurement pattern will be described below.
When it is determined in step S37 of
When removal using the FIB is performed, an ion beam such as a Ga ion is irradiated to the removal region, and the template constitutional material is removed by the sputtering technique. Alternatively, an etching gas is introduced, the etching gas is excited by the ion beam, and the template constitutional material of the removal region is selectively etched. When the removal using the EB is performed, an etching gas is introduced, the etching gas is excited by the electron beam, and the template constitutional material of the removal region is selectively etched. The correction position accuracy of the FIB is about 3 to 4 nm, the correction position accuracy of the EB is about 2 to 3 nm, and thus even a fine line-and-space pattern can be locally etched. As a result, obtained is the completed template 10B including the template substrate 11 in which the portion (the convex structure) presented in the space pattern 212 of the line-and-space pattern of the measurement pattern 22 in the transfer region 12 is removed.
In the third embodiment, the non-completed template 10A has the structure in which the measurement pattern 22 overlaps the device pattern 21 in the transfer region 12, and after the positional deviation measurement using the measurement pattern 22 ends, only the measurement pattern 22 is removed without breaking up the device pattern 21. Thus, in addition to the effect of the second embodiment, it is possible to obtain an effect by which even when the pattern such as the line-and-space pattern is formed on the whole transfer region 12, the measurement pattern 22 is formed in the transfer region 12, and the measurement pattern 22 in the transfer region 12 can be removed in the completed template 10B.
Further, in the first to third embodiments, the position deviation measurement is performed after the device pattern 21 and the measurement pattern 22 are formed in the template. However, the pattern used to form the measurement pattern in the developed resist pattern 52a or the pattern used to form the measurement pattern in the patterned mask layer 51 may be measured. In these cases, when it is determined that the positional deviation is not within the allowable range, the electron beam lithography resist 52 or the mask layer 51 may be removed, the mask layer 51 and the resist pattern 52a may be formed on the same template substrate 11 again, and then the same process may be performed. When the positional deviation measurement is measured using the pattern used to form the measurement pattern 22 is performed and the position deviation is not within the allowable range, since the template substrate 11 is not processed yet, the electron beam lithography resist 52 or the mask layer 51 has only to be removed, and the template substrate 11 need not be discarded. Consequently, there is an effect by which the manufacturing cost of the template can be reduced.
In the above description, the measurement pattern 22 on the transfer region 12 is removed, but the measurement pattern 22 on the kerf 13 may be also removed. In addition, the above description has been described in connection with the example in which a single measurement pattern 22 is arranged on the transfer region 12, but a plurality of measurement patterns 22 may be arranged.
Further, in the above description, although the measurement pattern 22 is formed in transfer region 12 and the non-transfer region (kerf 13), the measurement pattern 22 may be formed in at least the transfer region 12.
In the first to third embodiments, the positional deviation measurement and the template determining method using the same have not been described in detail. As described in the above embodiment, as the measurement pattern 22 is arranged on the transfer region 12 as well as the kerf 13, compared to the related art in which the measurement pattern 22 is arranged only on the kerf 13 and the positional deviation measurement is performed, the number of measurement points increases, and the template can be managed with a high degree of accuracy.
Here, the process of measuring the positional deviation of the template will be described. The positional deviation measurement using the measurement pattern 22 is performed using the measurement pattern 22 on the kerf 13 and the measurement pattern 22 on the transfer region 12, but this measurement can be performed using various methods. For example, the measurement patterns 22 on the kerf 13 and the transfer region 12 may be simultaneously measured. Alternatively, the measurement pattern 22 on the kerf 13 may be first measured, and then the measurement pattern 22 on the transfer region 12 may be measured.
(1) A case in which the measurement patterns 22 on the kerf 13 and the transfer region 12 are simultaneously measured.
In this case, it is determined whether or not the positional deviation is within the allowable range using the positional deviation measurement at all measured points (the measurement patterns 22).
(2) A case in which the measurement pattern 22 on the kerf 13 is first measured, and then the measurement pattern 22 on the transfer region 12 is measured.
In this case, the positional deviation measurement is first performed using the measurement pattern 22 on the kerf 13, and a first determination on whether or not the positional deviation is within the allowable range. Here, when it is determined that the positional deviation is not within the allowable range, the process of discarding template is performed, and a second determination which will be described below is not performed. However, when it is determined that the positional deviation is within the allowable range, the positional deviation measurement is further performed using the measurement pattern 22 on the transfer region 12, and the second determination on whether or not the positional deviation is within the allowable range is performed. Here, when it is determined that the positional deviation is not within the allowable range, the process of discarding template is performed, whereas when it is determined that the positional deviation is within the allowable range, the template can be used as the completed template 10B.
In other words, when the positional deviation on the kerf 13 is within the allowable range but the positional deviation on the transfer region 12 is not within the allowable range, the template is discarded.
Further, in this process, the value of the allowable range used in the first determination may differ from the value of the allowable range used in the second determination. For example, the values of the allowable ranges may be set such that a rough determination is performed as the first determination, and an accurate determination is performed as the second determination. As the two-step determination is performed, the accurate determination whether or not the template is to be discarded can be precisely performed, and even when the number of measurement points increases, the determination process on whether or not the template is to be discarded can be effectively performed.
According to the fourth embodiment, the first determination of measuring the measurement pattern 22 on the kerf 13 and determining whether or not the positional deviation is within the allowable range using the measurement result and the second determination of determining whether or not the positional deviation is within the allowable range using the measurement pattern 22 on the transfer region 12 when it is determined in the first determination that the position deviation is within the allowable range are performed in order. Consequently, since the second determination is not performed on the template that is determined in the first determination not to be within the allowable range, there is an effect by which the determination process can be effectively performed. In addition, there is an effect by which the accurate determination can be performed on whether or not the template can be used.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
This application is based upon and claims the benefit of priority from U.S. Provisional Application No. 61/756,087, filed on Jan. 24, 2013; the entire contents of which are incorporated herein by reference.
Number | Date | Country | |
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61756087 | Jan 2013 | US |