This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2021-040738, filed on Mar. 12, 2021, the entire contents of which are incorporated herein by reference.
The embodiments of the present invention relate to a template and a manufacturing method thereof.
In nanoimprinting that can form a fine pattern in a semiconductor device, a template having a uneven pattern region is pressed against resist that has been applied to a film to be processed. Accordingly, the uneven pattern is transferred to the resist. However, pattern roughness on the template is also transferred as it is.
and
Embodiments will now be explained with reference to the accompanying drawings. The present invention is not limited to the embodiments. In the present specification and the drawings, elements identical to those described in the foregoing drawings are denoted by like reference characters and detailed explanations thereof are omitted as appropriate.
A template according to the present embodiment includes a substrate and a first layer. The substrate includes a first face having a pattern, and contains a first element. The first layer is in contact with the first face, and contains a compound having the first element and a second element different from the first element, the density of the compound in the first layer being higher than the density of the compound in the substrate.
The template 1 includes a substrate 10 and a compound-containing layer 20.
The substrate 10 includes a face F1 and a face F2 on the side opposite to the face F1. The face F1 of the substrate 10 is provided with an uneven pattern 13. In nanoimprinting, the template 1 is pressed against resist that has been applied to a film to be processed, so that the uneven pattern 13 is transferred to the resist.
The uneven pattern 13 includes protrude patterns 11 and recess patterns 12. Upper face portions of the protrude patterns 11 correspond to an upper face F11. Bottom face portions of the recess patterns 12 correspond to a bottom face F12. Sidewall portions of the protrude patterns 11 correspond to side faces F13. It should be noted that the +Z-direction, which is a direction in which the protrude patterns 11 protrude, is assumed as the upward direction, and the −Z-direction, which is a direction in which the recess patterns 12 are recessed, is assumed as the downward direction.
The substrate 10 is a quartz glass substrate, for example. Thus, the substrate 10 contains silicon dioxide (SiO2). In addition, the substrate 10 also contains a first element. In such a case, the first element is silicon (Si), for example.
The compound-containing layer 20 is provided on the face F1 along at least the uneven pattern 13. The compound-containing layer 20 is provided on the surface layer of the uneven pattern 13 so as to be exposed from the substrate 10. As described below, the compound-containing layer 20 can reduce roughness of the uneven pattern 13.
The compound-containing layer 20 contains a compound having the first element and a second element different from the first element, and the density of the compound in the compound-containing layer is higher than that in the substrate 10. The second element is an element not contained as a main material of the substrate 10. For example, the second element is carbon (C). The compound of the compound-containing layer 20 is a silicon compound, such as silicon carbide (SiC) or silicon oxycarbide (SiOC), for example. More specifically, the compound-containing layer 20 is a mixed layer of a compound and a material of the substrate 10. That is, the surface layer of the face F1 of the substrate 10 contains a mixture of silicon carbide and silicon dioxide. It should be noted that the compound-containing layer 20 may be a single layer of a compound.
Described below is an example in which the material of the substrate 10 is quartz, the first element is silicon, the second element is carbon, and the compound of the compound-containing layer 20 is silicon carbide.
Silicon carbide in the compound-containing layer 20 can be identified by confirming its electronic state using X-ray photoelectron spectroscopy, for example. The density of the compound-containing layer 20 can be measured using X-ray reflectivity (XRR), for example. The density of silicon carbide is about 3.21 g/cm3, for example. The density of quartz is about 2.21 g/cm3, for example. In addition, the density of the mixed layer is about 2.25 g/cm3, for example.
The compound-containing layer 20 may contain carbon ions and silicon dioxide. This is because not all of the carbon ions necessarily react with silicon in the substrate 10. Thus, the density of carbon ions in the compound-containing layer 20 may be higher than that in the substrate 10.
The compound-containing layer 20 is an ultrathin film. The thickness of the compound-containing layer 20 is less than or equal to 3 nm, for example.
In the example illustrated in
Next, a method of manufacturing the template 1 will be described.
First, as illustrated in
Next, as illustrated in
The material film 30 is formed by plasma-based ion implantation and deposition (PBII&D), for example. In PBII&D, ion implantation and deposition of the material film 30 are performed. In PBII&D, an ion energy of about 100 V is added per carbon ion, for example, depending on a reactant gas used for deposition. The ion energy influences the intensity of ion implantation. As the accelerating voltage is higher, higher ion energy is added, and thus, carbon ions enter the substrate 10 more deeply. Examples of the reactant gas used for deposition include methane (CH4), acetylene (C2H2), and toluene (CHB).
When carbon ions are ion-implanted into the substrate 10, Si—O bonds in silicon dioxide of quartz are broken, and then, silicon and carbon are combined to form silicon carbide. In this manner, the compound-containing layer 20 is formed on the outermost layer of the substrate 10. The compound-containing layer 20 is formed substantially at the same time as the material film 30 is formed, for example.
It should be noted that the method of forming the compound-containing layer 20 and the material film 30 is not limited to PBII&D, and other methods may also be used. For example, to efficiently form the compound-containing layer 20, it is also possible to use other methods that allow active species present during deposition of the material film 30 to be ion-implanted into the surface layer of the substrate 10. Alternatively, it is also possible to use other methods of forming the compound-containing layer 20 without forming the material film 30.
After the step in
Next, roughness will be described along a manufacturing flow.
First, as illustrated in
The upper face F11, the bottom face F12, and the side face F13 of the uneven pattern 13 are ideally flat. However, in practice, as the upper face F11, the bottom face F12, and the side face F13 are magnified, minute protrusions and recesses (i.e., roughness) are also magnified to a nonnegligible level. Roughness can be measured down to the atomic size, for example. The amplitude of the roughness protrusions 131 and the roughness recesses 132 is less than or equal to 10% to 20% of the amplitude of the uneven pattern 13, for example. The smaller the uneven pattern 13, the more difficult it is to reduce roughness relative to the uneven pattern 13. Nanoimprinting has high transfer performance. Thus, the uneven pattern 13 of the template 1 is transferred as it is. Therefore, there is a possibility that the roughness of the uneven pattern 13 may also be transferred as it is. Thus, the template 1 with roughness less than or equal to a predetermined tolerance is typically used in nanoimprinting.
Next, as illustrated in
Next, as illustrated in
As described above, according to the first embodiment, the compound-containing layer 20 is provided so as to be exposed on the surface layer of the substrate 10 along the uneven pattern 13. Accordingly, roughness can be reduced.
The compound-containing layer 20 is a film containing silicon carbide (SiC) as described above. Silicon carbide has characteristics intermediate between those of silicon (Si) and diamond (C), and has excellent hardness. As an index of scratch resistance, the modified Mohs scale is used. The modified Mohs scale of quartz is 8, and the modified Mohs scale of silicon carbide is 13. Thus, silicon carbide of the compound-containing layer 20 has higher scratch resistance than quartz of the substrate 10. Silicon carbide in the surface layer of the uneven pattern 13 serves as a hard film coat. This can suppress defects, such as scratches on the uneven pattern 13, which would deteriorate the quality of the transferred pattern.
As another method of forming a silicon carbide film, thermal CVD (chemical vapor deposition) using a source gas containing Si and C may be used, for example. The process temperature of thermal CVD is typically as high as about 2000° C. The temperature is higher than the process temperature (for example, about 1900° C.) of quartz. Thus, it is difficult to deposit silicon carbide on the uneven pattern of quartz with high accuracy using thermal CVD.
In contrast, in the first embodiment, the material film 30 is deposited on the uneven pattern 13 of quartz at room temperature using PBII&D, and also, a silicon carbide film is formed. Accordingly, the uneven pattern 13 of quartz covered with an ultrathin silicon carbide film can be manufactured without through a high-temperature process.
It should be noted that the material of the substrate 10 is not limited to quartz and may be other materials. The compound of the compound-containing layer 20 is not limited to silicon carbide and may be other compounds.
A first protrude portion as the roughness protrusions 131 may be interpreted as at least one of the roughness protrusions 131. A first recess portion as the roughness recesses 132 may be interpreted as at least one of the roughness recesses 132.
First, as illustrated in
Next, as illustrated in
The thickness of the material film 30 is about 1 nm to about 3 nm, for example. The amount of deposition (i.e., thickness) of the material film 30 is controlled by controlling the deposition time, for example.
Next, as illustrated in
The step of removing the material film ends before the material film 30 is entirely removed. Portions of the protrude pattern 11 other than the roughness protrusions 131 remain covered with the material film 30. Thus, the material film 30 serves as a mask, and the substrate 10 and the compound-containing layer 20 other than the roughness protrusions 131 are not removed. Therefore, it is possible to selectively remove the roughness protrusions 131 while leaving the other parts of the uneven pattern 13, and thus improve the line edge roughness.
Next, as illustrated in
Next, as illustrated in
As described above, according to the second embodiment, not only is the material film 30 removed, but also the upper faces of the roughness protrusions 131 are partially removed in the step in
The other configurations of the template 1 according to the second embodiment are similar to the corresponding configurations of the template 1 according to the first embodiment. Thus, the detailed description thereof is omitted. The template 1 according to the second embodiment can obtain advantageous effects similar to those in the first embodiment.
In the second embodiment, the step of removing the roughness protrusions 131, which includes the step of depositing the material film 30 (
Selective removal of the roughness protrusions 131 is possible only while the material film 30 remains, and thus is temporally limited. Herein, if the material film 30 is entirely removed by etching using oxygen plasma and the material film 30 is deposited again, it becomes possible to selectively remove the roughness protrusions 131 again.
If the removal amount of the roughness protrusions 131 per step is increased, controllability may deteriorate. Thus, the removal amount of the roughness protrusions 131 per step is reduced, but the step of removing the roughness protrusions 131 is performed more than once.
First, after the step in
Next, the step of removing the roughness protrusions 131 illustrated in
After that, steps similar to those in and following
First, the uneven pattern 13 is formed on the substrate 10 as in the second embodiment (see
Next, as illustrated in
After that, steps similar to those in and following
In the third embodiment, it is possible to selectively expose the roughness protrusions 131 even if the removal amount of the material film 30 is reduced.
The other configurations of the template 1 according to the third embodiment are similar to the corresponding configurations of the template 1 according to the second embodiment. Thus, the detailed description thereof is omitted. The template 1 according to the third embodiment can obtain advantageous effects similar to those in the second embodiment. In addition, the template 1 according to the third embodiment may be combined with the modified example of the second embodiment.
First, the uneven pattern 13 is formed on the substrate 10 as in the second embodiment (see
Next, as illustrated in
Next, as illustrated in
Herein, the step of removing the material film 30 in the fourth embodiment is performed such that the etch selectivity between the material film 30 and the substrate 10 is substantially 1:1. When the etch selectivity is substantially 1:1, it is possible to etch the substrate 10 together with the material film 30 so as to maintain the surface shape of the material film 30 illustrated in
It should be noted that the etching rate is adjusted by adjusting the gas ratio, for example. The etching rate is adjusted according to the quality of the material film 30, for example.
After that, steps similar to those in and following
The other configurations of the template 1 according to the fourth embodiment are similar to the corresponding configurations of the template 1 according to the second embodiment. Thus, the detailed description thereof is omitted. The template 1 according to the fourth embodiment can obtain advantageous effects similar to those in the second embodiment. In addition, the template 1 according to the fourth embodiment may be combined with the modified example of the second embodiment.
First, as illustrated in
Next, as illustrated in
The way in which the material film 30 deposits on the uneven pattern 13 can be adjusted by adjusting the deposition conditions for the material film 30. To reduce the amount of deposition of the material film 30 on the sidewall portion, it is effective to reduce a radicalized carbon material during deposition of the material film 30. Using FCVA (filtered cathodic vacuum arc) for a plasma source, for example, can efficiently remove radical components.
When
The other configurations of the template 1 according to the fifth embodiment are similar to the corresponding configurations of the template 1 according to the second embodiment. Thus, the detailed description thereof is omitted. The template 1 according to the fifth embodiment can obtain advantageous effects similar to those in the second embodiment. In addition, the template 1 according to the fifth embodiment may be combined with the modified example of the second embodiment.
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 methods and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems 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.
Number | Date | Country | Kind |
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2021-040738 | Mar 2021 | JP | national |