CN109609907B

CN109609907B - Method for preparing metal nanostructure by self-absorption nanoimprint lithography

Info

Publication number: CN109609907B
Application number: CN201910102886.3A
Authority: CN
Inventors: 耿照新; 苏玥; 吕晓庆; 裴为华; 陈弘达
Original assignee: Institute of Semiconductors of CAS
Current assignee: Institute of Semiconductors of CAS
Priority date: 2019-01-31
Filing date: 2019-01-31
Publication date: 2020-01-21
Anticipated expiration: 2039-01-31
Also published as: CN109609907A

Abstract

The present disclosure provides a method for preparing a metal nanostructure by self-priming nanoimprint lithography, comprising: turning over the surface of the hard matrix nano-imprint template by using Polydimethylsiloxane (PDMS) to obtain a PDMS soft template; spin-coating a lower layer of glue on the surface of a substrate, heating and curing, and spin-coating an upper layer of glue on the surface of the lower layer of glue; covering the surface of the upper layer of glue with the PDMS soft template, heating and curing the upper layer of glue, and removing the PDMS soft template to obtain a grating structure; if the upper layer glue is negative glue, baking after exposure, and if the upper layer glue is positive glue, not exposing; forming an inverted structure by the upper layer glue and the lower layer glue on the substrate through development; and evaporating the metal, and stripping the lower layer glue, the upper layer glue and the metal positioned on the upper layer glue by a stripping process to form the metal nano structure.

Description

Method for preparing metal nanostructure by self-absorption nanoimprint lithography

Technical Field

The disclosure relates to the technical field of micro-nano manufacturing, in particular to a method for preparing a metal nano structure by self-absorption nano imprinting.

Background

With the development of nanoscience, the application thereof extends to various fields, and particularly, a preparation method of a nano structure gradually becomes a hot point of research. In 1995, professor Zhou Hua scientists at Princessan university proposed a nano-imprinting technique aiming at the limitation of exposure wavelength of a lithography process, and imprinted a nano pattern on a template on a substrate, because the nano-imprinting technique saved the control of complex links in the lithography process, and could break the diffraction limit, and large-area preparation of nano-structures, the technique aroused the interest of many researchers, obtained extensive research and application, became a new generation of nano-fabrication technique, and applied in various fields of semiconductor industry.

In the prior art, nanoimprinting is classified into two types, thermal imprint and ultraviolet curing imprint. The material for hot stamping is based on thermoplastic high polymer material, and the high polymer material is softened when heated, and the structure of the stamping template is copied to the molten high polymer film by external pressure, and then the stamping template is cooled and formed. The high temperature heating and cooling process can extend the imprinting period and reduce yield, while high pressure molding can increase template loss, while limiting the application of substrate materials that cannot withstand high pressure, requiring specialized imprinting equipment to provide large areas of uniform pressure and high temperature, which is costly. In the ultraviolet curing nano imprinting, the polymer is not heated and cooled to be molded any more, but is cured and molded by ultraviolet radiation, so that in order to ensure that the template and the substrate can be completely attached, more than one pressure is required to be applied, and the uniform preparation can be realized by the assistance of expensive imprinting equipment. In actual stamping, the structure of stamping glue is usually a positive mesa structure, a gold evaporation stripping process cannot be completed, nano-stamping is usually carried out on a gold film, and the preparation of a gold nano structure is completed in a gold etching mode.

Disclosure of Invention

Technical problem to be solved

In view of the above problems, it is a primary object of the present disclosure to provide a method for preparing metal nanostructures by self-priming nanoimprint so as to solve at least one of the above problems.

(II) technical scheme

To achieve the above objects, as one aspect of the present disclosure, there is provided a method for preparing a metal nanostructure by self-priming nanoimprint, including the steps of:

turning over the surface of the hard matrix nano-imprint template by using Polydimethylsiloxane (PDMS) to obtain a PDMS soft template;

spin-coating a lower layer of glue on the surface of a substrate, heating and curing, and spin-coating an upper layer of glue on the surface of the lower layer of glue;

covering the surface of the upper layer of glue with the PDMS soft template, heating and curing the upper layer of glue, and removing the PDMS soft template to obtain a grating structure;

if the upper layer glue is negative glue, baking after exposure, and if the upper layer glue is positive glue, not exposing;

forming an inverted structure by the upper layer glue and the lower layer glue on the substrate through development;

and evaporating the metal, and stripping the lower layer glue, the upper layer glue and the metal positioned on the upper layer glue by a stripping process to form the metal nano structure.

In some embodiments, the hard-based nano-imprint template comprises a silicon-based template, a quartz template, a polymer template, and is prepared by electron beam exposure, two-beam interference exposure, and a nano-imprint method.

In some embodiments, the PDMS soft template is obtained by mixing basic components of Sylgard184 and a curing agent in a certain ratio, pouring the mixture onto the hard matrix nano-imprint template, and heating and curing the mixture.

In some embodiments, the electron beam is used to evaporate metals including chromium, gold, silver, aluminum.

In some embodiments, the substrate comprises a silicon wafer, a quartz wafer, a silicon nitride wafer, ITO glass.

In some embodiments, the under layer gum development rate is greater than the over layer gum development rate, and the under layer gum thickness is greater than the evaporated metal thickness.

In some embodiments, the thickness of the supersize is less than the height of the nanostructures of the hard matrix nano-imprint template, and the supersize fills the nano-channels of the PDMS soft template by capillary force.

In some embodiments, in the developing step, the upper layer glue and the lower layer glue are dissolved in a developing solution, a first portion of the upper layer glue is developed to expose the lower layer glue under the first portion, a second portion of the upper layer glue is reserved as a mask, and the lower layer glue is undercut to form an inverted mesa structure.

In some embodiments, the thickness of the first portion of the topping adhesive is less than the thickness of the second portion.

In some embodiments, the upper layer of glue is AR-N-4340 negative glue and the lower layer of glue is LOL 2000.

(III) advantageous effects

According to the technical scheme, the method for preparing the metal nano structure by self-absorption nano imprinting has at least one of the following beneficial effects:

(1) the hard substrate nano-imprint template is turned to obtain the PDMS soft template with an opposite structure, the photoresist with a small viscosity coefficient is used as the imprint adhesive, the photoresist can automatically adsorb and fill the PDMS soft template under the action of capillary force, the required nano structure can be uniformly copied in a large area without pressurization of special nano-imprint equipment, and the operation is simple and the cost is low.

(2) The double-layer glue structure is adopted, and the reverse stage is formed through development to realize the gold evaporation stripping process so as to prepare the gold nanostructure. Therefore, the self-absorption imprinting preparation method of the nano structure has the advantages of large area and low cost, and meanwhile, the problem that the regular trapezoid structure obtained in the traditional nano imprinting process cannot be stripped can be solved by adopting a double-layer glue process technology, so that the self-absorption imprinting preparation method is more easily and widely applied.

Drawings

In order to more clearly illustrate the technical solutions and embodiments of the present disclosure, the drawings used in the prior art and the implementation cases will be described below, and it is obvious that the drawings in the following description are only some embodiments of the present disclosure, and other drawings can be obtained by those skilled in the art without inventive efforts.

Fig. 1-3 are flow charts of methods for preparing metal nanostructures by self-priming nanoimprint lithography according to the present disclosure.

Fig. 4 is a flow chart of a method for preparing a metal nanostructure by self-priming nanoimprint lithography according to the present disclosure, and specifically, a DVD is used as a hard template.

Fig. 5 is an SEM image of the photoresist on the silicon substrate after imprint development of different underlying photoresist thicknesses obtained by the imprint method provided in the embodiments of the present disclosure. (wherein, (a) the lower layer glue thickness is 300nm, the development lasts for 50s, (b) the lower layer glue thickness is 200nm, the development lasts for 40s, and (c) the photoresist stripper thins the lower layer glue to 100nm, and the development lasts for 25 s).

FIG. 6 is an SEM image of photoresist developed on a silicon substrate at different times (wherein the thickness of the underlying photoresist is 200nm, (a) is 22s for development, (b) is 26s for development, and (c) is 30s for development).

Fig. 7 is SEM images of chrome gold of different thicknesses obtained by the imprinting method provided in the embodiments of the present disclosure. The method comprises the steps of (a) before gold evaporation with the lower layer glue thickness of 200nm, (b) electron beam evaporation of Cr (10nm) and Au (120nm) for the nanostructure of the figure (a), (c) SEM picture after stripping of the nanostructure of the figure (b), (d) thickness of 300nm for the developed lower layer glue, (e) electron beam evaporation of Cr (10nm) and Au (200nm) for the nanostructure of the figure (d), (f) SEM picture after stripping of the nanostructure of the figure (e).

< description of symbols >

10-hard matrix nano-imprint template; 11. 23-PDMS soft template; 12. 20-lower layer glue; 13. 21-a substrate; 14. 22-upper glue layer; 15. 24-metal.

Detailed Description

For the purpose of promoting a better understanding of the objects, aspects and advantages of the present disclosure, reference is made to the following detailed description taken in conjunction with the accompanying drawings.

The present disclosure provides a method for preparing a metal nanostructure by self-priming nanoimprint with a large area and low cost, as shown in fig. 1 to 3, the method for preparing a metal nanostructure by self-priming nanoimprint comprises:

step 1, preparing a soft imprinting template as shown in fig. 1:

a hard matrix nano-imprinting template 10 is adopted to turn over to obtain a PDMS soft imprinting template 11 (referred to as PDMS soft template for short), as shown in FIG. 1, the hard matrix nano-imprinting template is provided with a nano-structure, and correspondingly, the PDMS soft imprinting template obtained by turning over is also provided with a nano-structure, and the structures of the two are opposite; the PDMS is adopted to turn over the hard substrate nano-imprinting template, so that the effect of protecting the template is achieved, and the defect of uneven pressure caused by direct imprinting of the hard template is overcome by the PDMS soft template.

Step 2, spin coating the substrate lower layer glue, as shown in fig. 2:

and spin-coating the lower layer glue 12 applied to the stripping process double-layer glue on the surface of the substrate 13, and heating and curing.

Step 3, spin coating the upper layer glue on the substrate, as shown in fig. 2:

and spin-coating an upper layer adhesive 14 applied to the double-layer adhesive in the stripping process on the surface of the lower layer adhesive. The upper layer of glue is made of common photoresist, the thickness of the spin coating is close to the height of the nano structure of the template, the nano channel of the PDMS soft template is filled through capillary force, a nano stamping machine is not needed for pressurization, equipment limitation is avoided, and expensive stamping equipment and complex operation procedures are omitted.

Step 4, self-priming imprinting and curing, as shown in fig. 3:

and covering the surface of the photoresist by using the PDMS soft template, automatically adsorbing and filling the PDMS nano channel on the PDMS soft template by using the upper layer of glue under the action of capillary force without pressurizing, and heating and curing the upper layer of glue to obtain the grating structure (nano grating structure).

Step 5, exposure:

and step 6, developing:

and developing in a developing solution, namely developing and removing the residual glue part of the upper layer glue in the pressing way, exposing the lower layer glue, wherein the developing speed is far higher than that of the upper layer glue, and inwards undercutting to form an inverted platform structure.

Step 7, evaporating the metal, as shown in fig. 3:

the electron beam evaporates a metal 15 such as chromium, gold, silver, aluminum, etc.

Step 8, peeling, as shown in fig. 3:

and stripping the lower layer glue, the upper layer glue on the lower layer glue and the metal on the upper layer glue by a stripping process to form the metal nano structure (namely the metal nano structure which is reserved after stripping and is positioned on the substrate and is in direct contact with the substrate).

According to the method, the double-layer glue process is adopted, the pattern with the glue thickness higher than the height of the nano structure can be obtained, the inverted platform structure can be formed, metal evaporation and stripping are completed, the metal nano structure is obtained, the problem that the metal nano structure cannot be stripped in the traditional nano imprinting process is solved, and the complex process and high cost of pattern transfer by etching are avoided.

Specifically, in the step 1, the hard substrate nano-imprint template includes a silicon-based template, a quartz template, a polymer template, and the like. Mixing basic components of Sylgard184 and a curing agent according to a certain proportion, pouring the mixture on a nano-structure template, and heating and curing to obtain the PDMS soft template.

In the step 2, the size of the substrate is close to that of the hard substrate nano-imprinting template, and the substrate is the maximum area which can be prepared, and the substrate comprises a silicon wafer, quartz, a silicon nitride substrate, an ITO glass substrate and other hard substrate substrates. The lower layer glue and the upper layer glue used for the stripping process have the same developing solution, and the developing rate of the lower layer glue is far greater than that of the upper layer glue. The lower layer glue can be smoothly stripped when the thickness of the lower layer glue is larger than that of the evaporated gold, and the developing rate of the lower layer glue is determined by the glue drying temperature and time of the lower layer glue.

In the step 3, the upper layer glue is spin-coated on the cured lower layer glue, but the thickness of the upper layer glue is close to the height size of the nano structure of the hard substrate nano imprinting template. By adopting a double-layer glue (lower-layer glue and lower-layer glue) process, a photoresist inverted platform structure can be manufactured, pattern transfer is realized through a gold evaporation stripping process subsequently, and the defect that an inverted platform cannot be manufactured in the traditional nanoimprint is overcome.

In the step 4, the nano-channels of the PDMS are directly filled with the photoresist due to the capillary force in the imprinting process without applying pressure, and the pre-baking curing condition is determined by the used upper layer of the photoresist.

In the step 5, if the upper layer glue is a negative glue, post-exposure baking is required, and the development rate can be further reduced by increasing the exposure dose and the post-baking temperature. If the selected upper layer glue is positive glue, the whole experimental process is ensured not to be exposed.

In the step 6, the upper layer of glue and the lower layer of glue are both dissolved in the developing solution, and the developing speed is controlled by adjusting the ratio of the developing solution. Because the developing speed of the lower layer glue is far greater than that of the upper layer glue, in the developing process, the thin glue part of the upper layer glue is developed and removed, the lower layer glue is exposed, the lower layer glue is developed quickly, and the thick glue part of the upper layer glue is still reserved, so that the lower layer glue is etched to form an inverted structure, and the stripping process is facilitated.

In the step 7, the electron beam evaporates chromium to increase the adhesion between the gold and the substrate, and the thickness of the electron beam evaporated gold is smaller than that of the lower layer glue, so that the stripping is smoothly realized.

In the step 8, the substrate is placed in acetone, low-power ultrasonic treatment is carried out to realize stripping, and the lower layer glue, the upper layer glue and the metal positioned on the upper layer glue are removed to form the metal nano structure.

In a specific embodiment, as shown in fig. 4, an embodiment of preparing a metal nano grating on a silicon substrate by using a PDMS to flip a DVD disc to obtain a PDMS soft template is described, in which the method for preparing a metal nano structure by self-priming nano imprinting in this embodiment includes:

mixing basic components of Sylgard184 and a curing agent in a ratio of 10: 1 in a disposable plastic cup, stirring and fully mixing, putting the mixture into a vacuum drying oven, vacuumizing at normal temperature, preferably, vacuumizing for 30 minutes, and removing bubbles to obtain colorless and transparent liquid PDMS.

Separating the two polycarbonate layers of the DVD from the edge to obtain an opaque aluminum reflecting layer, a polycarbonate layer and a transparent polycarbonate layer, putting the transparent surface into ethanol for ultrasonic cleaning for 10 minutes, removing dye, putting into deionized water for ultrasonic cleaning for 10 minutes, drying by a nitrogen gun, winding the edge by a high-temperature adhesive tape, and sticking a hole in the middle by the adhesive tape to form a PDMS mold turning die so as to avoid PDMS exudation.

Pouring the liquid PDMS with the bubbles removed into the cleaned DVD template, putting the DVD template into a vacuum drying oven for vacuumizing at normal temperature, preferably for 30 minutes, removing the bubbles, then putting the DVD template on a horizontal hot plate, standing for a period of time to ensure that the thickness of the PDMS is uniform, heating and curing the PDMS at the curing temperature of 60-70 ℃ to avoid the deformation of the DVD polycarbonate layer caused by overhigh temperature, preferably for 30 minutes. And taking down the DVD disc after curing is finished, and peeling the PDMS from the surface of the disc by using tweezers to obtain the PDMS soft template 23.

Heating a 4-inch silicon substrate 21 with piranha water (the volume ratio of hydrogen peroxide to sulfuric acid is 1: 3) at 170 ℃ for 1h, washing with deionized water for 20 times, drying with a nitrogen gun at 120 ℃ for 30min to remove surface water vapor, polishing with a plasma degumming machine for 2min, wherein the oxygen flow is 300mL/min, and the power is 300W to remove impurities, thus obtaining a silicon wafer with a clean surface. HMDS is coated by steaming, so that the adhesive property of the adhesive is improved, and the adhesive is prevented from being floated. The lower layer glue 20 of the double-layer glue process for stripping is spin-coated, wherein LOL2000 is selected, the glue thickness is determined by the rotating speed, the glue thickness is 300nm at 2000rpm, the glue thickness is 200nm at 6000rpm, then the lower layer glue is heated and cured, and the smaller glue thickness can be obtained by removing the glue by oxygen. And the time and temperature of heating and curing can adjust the developing speed of the lower layer glue. The temperature of drying glue is 150 ℃ and the time is 3 min.

And (3) spin-coating an upper layer adhesive 22 on the cured lower layer adhesive 20, paying attention to the fact that the thickness of the upper layer adhesive is matched with the grating height of the DVD, diluting AR-N-4340 by using AR300-12, wherein the dilution ratio is 4: 1, the whirl coating rotating speed is 6000rpm, the adhesive thickness can be 120nm, then, a PDMS soft template is used for imprinting, the nanometer channels of the PDMS can be directly filled due to capillary force, and the pre-drying temperature is 110 ℃ and the pre-drying time is 150 s. After cooling, the PDMS soft template 20 is slowly removed to obtain a grating pattern of the cured topcoat 22. The PDMS is used for turning over the DVD optical disk to obtain a soft template for preparing the nano grating in a large area, pressure is not required to be applied, the nano channel is filled by self absorption of capillary force, and the cost of the traditional nano imprinting is greatly reduced. And the double-layer glue process is adopted to obtain a reverse structure, so that gold is evaporated and stripped to obtain a metal grating structure, and low-cost nano pattern transfer is realized.

Because the selected upper layer adhesive AR-N-4340 is a negative adhesive, post-baking is needed, the exposure dose and the post-baking temperature and time are increased, and the developing speed can be further reduced. The exposure dose is 200mJ/cm2, the postbaking temperature is 120 ℃, and the time is 2 min.

KMP PD23-II and deionized water are diluted according to the ratio of 2: 1 to prepare a developing solution, the upper layer glue and the lower layer glue can be dissolved in the developing solution, but the developing rate of the lower layer glue 20 is far greater than that of the upper layer glue 12, as the developing is carried out, the thin glue part pressed by the upper layer glue 22 is developed to expose the lower layer glue, the lower layer glue is developed rapidly, the thick glue part of the upper layer glue still remains, the lower layer glue 20 is undercut to form a reverse structure, the stripping process is facilitated, and the developing time is 22s-30 s. And drying the surface moisture by using a nitrogen gun after the development is finished.

Removing residual oxygen plasma from bottom mold before steaming goldPhotoresist is printed, bottom die printing conditions are that oxygen flow is 300mL/min, power is 200W, time is 1min, and a Faraday cage is added. Electron beam evaporation of chrome gold 24 with 10nm of chrome as an adhesion agent for gold and substrate silicon, and gold evaporation rate

Vacuum degree of 2X 10-⁴Pa, temperature 60 ℃. The stripping was performed using NMP, a stripping solution for the underlying gel LOL 2000.

Figure 5 is a SEM image of the photoresist on a silicon substrate after imprint development of different underlying photoresist thicknesses,

FIG. 6 is an SEM image of photoresist developed on a silicon substrate at different times, and FIG. 7 is an SEM image of the photoresist stripped by evaporating gold of different thicknesses after imprint development.

According to the method for preparing the metal nanostructure by self-absorption nanoimprint, a cheap DVD (digital video disk) is selected as an original template by using an imprint technical principle, a PDMS (polydimethylsiloxane) is turned over to obtain an imprint soft template, and a large-area nano grating is manufactured on a substrate, so that an expensive imprint template and imprint equipment are saved, the defect of a hard template is overcome, the experiment cost is greatly reduced, the whole process is simple and feasible, and the experiment efficiency is improved; and the double-layer glue process is combined with the nano-imprinting to obtain an inverted platform structure, and the pattern is transferred by using the stripping process, so that the problem that the regular trapezoid structure of the traditional nano-imprinting cannot be stripped is solved.

The above embodiments are provided to explain the purpose, technical solutions and beneficial results of the present disclosure in further detail, it should be understood that the above embodiments are merely exemplary of the present disclosure and are not intended to limit the present disclosure, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present disclosure should be included in the scope of the present disclosure.

Further, the above definitions of the various elements and methods are not limited to the various specific structures, shapes or arrangements of parts mentioned in the examples, which may be easily modified or substituted by those of ordinary skill in the art.

It should be noted that directional terms, such as "upper", "lower", "front", "rear", "left", "right", and the like, mentioned in the embodiments are only directions referring to the drawings, and are not intended to limit the scope of the present disclosure. Throughout the drawings, like elements are represented by like or similar reference numerals. Conventional structures or constructions will be omitted when they may obscure the understanding of the present disclosure. And the shapes and sizes of the respective components in the drawings do not reflect actual sizes and proportions, but merely illustrate the contents of the embodiments of the present disclosure. Furthermore, in the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

Furthermore, the word "comprising" or "comprises" does not exclude the presence of elements or steps other than those listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

The use of ordinal numbers such as "first," "second," "third," etc., in the specification and claims to modify a corresponding element does not by itself connote any ordinal number of the element or any ordering of one element from another or the order of manufacture, and the use of the ordinal numbers is only used to distinguish one element having a certain name from another element having a same name.

Similarly, it should be appreciated that in the foregoing description of exemplary embodiments of the disclosure, various features of the disclosure are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various disclosed aspects. However, the disclosed method should not be interpreted as reflecting an intention that: that is, the claimed disclosure requires more features than are expressly recited in each claim. Rather, as the following claims reflect, disclosed aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this disclosure.

The above-mentioned embodiments are intended to illustrate the objects, aspects and advantages of the present disclosure in further detail, and it should be understood that the above-mentioned embodiments are only illustrative of the present disclosure and are not intended to limit the present disclosure, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present disclosure should be included in the scope of the present disclosure.

Claims

1. A method for preparing a metal nanostructure by self-absorption nanoimprint lithography comprises the following steps:

evaporating metal, and stripping the lower layer glue, the upper layer glue and the metal positioned on the upper layer glue through a stripping process to form a metal nano structure;

the developing rate of the lower layer glue is greater than that of the upper layer glue, and the thickness of the lower layer glue is greater than that of the evaporation metal.

2. The method for preparing a metal nanostructure by self-priming nanoimprint lithography according to claim 1, wherein the hard matrix nanoimprint template comprises a silicon-based template, a quartz template, a polymer template, and is prepared by electron beam exposure, two-beam interference exposure, and a nanoimprint method.

3. The method for preparing a metal nanostructure through self-priming nanoimprint according to claim 1, wherein the PDMS soft template is obtained by mixing basic components of Sylgard184 and a curing agent according to a certain ratio, pouring the mixture onto the hard matrix nanoimprint template, and heating and curing the mixture.

4. The method for preparing metal nanostructures according to claim 1, wherein electron beam evaporation of metal is used, and the metal comprises chromium, gold, silver, aluminum.

5. The self-priming nanoimprint lithography method for preparing metal nanostructures according to claim 1, wherein the substrate comprises a silicon wafer, a quartz wafer, a silicon nitride wafer, or ITO glass.

6. The self-priming nanoimprint lithography method for preparing metal nanostructures of claim 1, wherein the thickness of the supersize is smaller than the height of the nanostructures of the hard matrix nanoimprint template, and the supersize fills the nanochannel of the PDMS soft template by capillary force.

7. The self-priming nanoimprint lithography method for preparing metal nanostructures according to claim 1, wherein, in the developing step, the upper layer glue and the lower layer glue are dissolved in a developing solution, a first portion of the upper layer glue is developed away to expose the lower layer glue under the first portion, a second portion of the upper layer glue is reserved as a mask, and the lower layer glue is undercut to form an inverted mesa structure.

8. The self-priming nanoimprint lithography method of claim 7, wherein the first portion of the supersize has a thickness that is less than a thickness of the second portion.

9. The self-priming nanoimprint lithography method for preparing metal nanostructures according to claim 1, wherein the upper layer glue is AR-N-4340 negative glue, and the lower layer glue is LOL 2000.