KR20120124476A - Method and process for metallic stamp replication for large area nanopatterns - Google Patents

Abstract

The present invention provides a method and process for obtaining a metal stamp from an intermediate polymer stamp, comprising providing a first imprint layer on top of a first polymer layer and imprinting the structure to obtain an intermediate stamp. It relates to a method and a process. If the imprinted polymer is non-conductive, a conductive layer is provided on top of the structure to obtain a seed layer, the metal is plated on top of the intermediate polymer stamp to obtain a metal stamp, and then an intermediate from the metal stamp. Detach the stamp. The stamp duplication is achieved with high yield and low cost by the present invention.

Description

METHOD AND PROCESS FOR METALLIC STAMP REPLICATION FOR LARGE AREA NANOPATTERNS}

The present invention relates to the replication of metal stamps by imprinting lithography technology using an intermediate polymer stamp (IPS) consisting of micro and nano structures.

Imprint lithography invention of Kondo (NTT), a low cost and high yield manufacturing process [Kondo, M., Patent no. JP 22389, 1979 is widely used in many applications, such as photonics, magnetic data storage, displays, nano-micro-electromechanical devices (NEMS, MEMS), nano-micro-electronics, biotech and chemical synthesis Being adopted. However, one of the key issues of the invented technology is the manufacture of imprint stamps with nanopatterns at high cost and high resolution at a low cost, which is at the same time a long distance over a large area at low cost. -random order) to pattern arbitrary nanostructures. JJ Wang, et al. J. lightwave technol., Vol. 23, pp. 474-485, 2005; In B. Heidari, et al, J. Vac. Sci. Technol., B 17 (6), pp 2961-2964, Nov / Dec 1999]. However, stamp replication is still an important issue in nano imprint lithography (NIL). The manufacture of conventional silicon stamps with nanoscale patterns is known to be based on expensive e-beam lithography, followed by dry etching or metal lift-off. However, silicon stamps are too fragile to use in compression or injection templates for mass production and are therefore not suitable for mass production in industrial applications. For example, Hirai et al. Found that Si-stamps could hardly be used more than 20 times in an imprint process where a high pressure impact was repeatedly applied to the master stamp captivity. [Y. Hirai , et al., Jpn. J. Appl. Phys., Vol. 41, pp. 4186-4189, 2002. Nickel stamps, on the other hand, not only provide high mechanical strength and durability, but also allow for cost-effective manufacturing by electroforming processes. J. K. Luo, et al., Mater. Lett., Vol. 58, pp. 2306-2309, 2004; T. Haatainen, et al., Microelectron. Eng., Vol. 83, pp. 948-950, 2006; S. H. Hong, et al., Microelectron. Eng., Vol. 84, pp. 977-979, 2007]. However, molds suitable for electroforming must be anti-adhesive as well as conductive to the electroformed nickel stamps to facilitate the replication of multiple nickel stamps from one original mold. Silicon stamps as electroforming templates to facilitate separation [J. Kouba, et al., J. Phys. Conference Series, Vol. 34, p. 897 (2006)] or modified stamps [Y. Hirai, et al., Jpn. J. Appl. Phys. Vol. 41, p. 4186 (2002) have been made, but concentrated alkaline solvents should be used to dissolve the template. In this case the original mold is broken and only one nickel stamp can be provided. Another well known method is the use of structured and developed electron beam resists that act directly as galvanic forms for nickel electroforming.

Summary of the Invention

In order to reduce the manufacturing cost of nano-imprint lithography (NIL) and thereby further promote the application of NIL technology in the industry, a maximum amount of electron beam lithography (EBL) -resist master based Replicating nickel stamps has been found by the inventors to be of paramount importance. Recently, electroforming by familiar processes has made it easier to manufacture more Ni-stamps with the same structure as the original EBL-master. This means that only one EBL-master provides, by electroforming, one "father" Ni-stamp with inverting features. On the other hand, by performing additional electroforming based on the "Father" stamp, a "mother" stamp having the same structure as the EBL-master is obtained. Incidentally, the inventors have found that, in this way, the separation between the father stamp and the mother stamp becomes more and more severely deformed in the separation period, so that the small spaces, which are closely spaced, have a large area and a high aspect ratio. Since it is patterned, it has been found that only 10 mother stamps can be produced. In accordance with the present invention, the present inventors have introduced a novel method of copying large amounts of nickel stamps from the original master by a combined NIL and electroforming process. If a pattern identical to that of the original stamp was required, then one step NIL was performed, otherwise the two step NIL process would provide an inverted nanostructure on the nickel stamp after electroforming, for the pattern of the original template. Given the fact that a pattern that is inverted is not easily obtained, perhaps a two step NIL process is more promising.

One aspect of the present invention is a method for obtaining a metal stamp having the same structure as a master stamp from one or more intermediate stamps, comprising: providing a first imprint layer on top of a first carrier substrate; Imprinting the structure in the first imprint layer using the master stamp to obtain a first intermediate stamp; Providing a conductive layer on top of the structured first intermediate stamp to obtain a seed layer; Plating a metal on top of the seed layer to obtain a metal stamp; Provided by a method comprising separating a first intermediate stamp from a metal stamp.

Another aspect of the invention is a method for obtaining a metal stamp having a structure inverse to the structure of the master stamp, the metal stamp providing a second imprint layer on top of the second carrier layer; Imprinting a structure in a second imprint layer using the first intermediate stamp to obtain a second intermediate stamp; Providing a conductive layer on top of the second intermediate stamp to obtain a seed layer; Plating a metal on top of the seed layer to obtain a metal stamp; A method of obtaining from two or more intermediate stamps according to the step of separating the second intermediate stamp from the metal stamp.

The first and second carrier substrates may comprise a polymeric material and the first carrier substrate may comprise a transparent material. The second carrier substrate may comprise a transparent or opaque material, and such carrier substrates may comprise glass, semiconductor material or metal.

Moreover, the first and second imprint layers can be coated on top of the carrier substrate.

Anti-adhesive molecules may be provided in the resist prior to obtaining the seed layer, such that a seed layer of at least one atomic conductive layer thickness is sputtered on top of the first intermediate stamp structure. Can be.

To obtain a metal stamp having a structure that is inverse to the structure of the master stamp, the seed layer can be sputtered on top of the structure of the second intermediate stamp.

The conductive material may be a metal composed of one or more metals of nickel, gold, silver, titanium, copper and aluminum. The metal stamp can be electroplated on top of the conductive layer.

In addition, the imprinted structure in the imprint layer can include micro and nano structure sizes greater than 5 nm.

If the first imprint layer and the second imprint layer material are conductive polymers, the seed layer is not necessary. In this case, the sputtering step is not performed and the metal stamp is directly electroplated on top of the conductive polymer.

In addition, the separation step between the intermediate stamp and the metal stamp can be accomplished by mechanical demolding.

It can also be mentioned that the preparation of any of the above metal stamps can be carried out at a constant temperature in the range of 15 to 100 ° C., preferably 20 to 70 ° C.

1 shows a schematic diagram of a stamp replication process by electroforming using IPS as a galvanic-template.
Figure 2 shows a schematic diagram of a stamp duplication process by a two-step imprint process using an IPS imprinted substrate as a galvanic-template.
FIG. 3 shows a scanning electron microscope (SEM) and atomic force microscope (AFM) images of the produced nickel stamp with photonic crystal structure.
4 shows SEM and AFM images of the produced nickel stamp with the magnetic storage medium structure.
5 shows SEM and AFM images of an imprinted Si-substrate.
6 shows an SEM image obtained on a replicated nickel stamp.

DETAILED DESCRIPTION OF THE INVENTION

Provided herein are methods for replicating metal stamps in bulk and cost-effectively by combined nanoimprint lithography and electroforming. The method of the present invention involves pattern transfer to an Intermediate Polymer Stamp (IPS) where the IPS can be used directly as a Galvanic-Master Stamp to duplicate a metal stamp having the same nanostructure as that of the original Master Stamp. Step imprinting). IPS can also be further used to imprint resists such as, but not limited to, thermoplastic / UV-curable resists (two step imprinting). In this way, the nanostructure on the electroformed metal stamp will be reversed for the structure of the original master stamp. The present invention provides that imprinting and demolding occur only between the soft polymer material and the master stamp to prevent fracture of the hard material, and contaminants such as dust particles present at the interface between the master stamp and the IPS may be surrounded by the IPS. As such, it significantly extends the life of the original master stamp. Direct electroforming from the IPS based master stamp will facilitate separation between the master stamp and the metal stamp after electroforming. By using IPS-based nanoprinting, it has been shown that, using one master stamp, about 1000 IPS can be produced without contaminating or damaging the master stamp, which means that 1000 metal stamps are based on one master stamp. This means that it can be replicated by electroforming. Moreover, even if the original master stamp is opaque or UV-opaque, UV-imprint can still be performed between the master stamp and the IPS and also between the IPS and other opaque / UV-opaque substrates because the selected IPS material is UV-transparent. have.

The advantages of using IPS to transfer nanostructures on nickel stamps from the original imprint stamp are as follows:

1) The conformability of the IPS makes it adaptable to non-planar master stamps or substrates.

2) Because IPS is UV-transparent, even if the original stamp is opaque, IPS still allows UV processing.

3) The use of IPS prevents rupture on the hard material. For example, if some dust / particles are present between the IPS and the substrate, the dust / particles will then be enclosed in the polymer without causing cracks on the stamp.

4) Demolding occurs only between the polymer and the hard material to prevent demolding damage.

According to Fig. 1, a nickel-stamp having the same structure as that of the original stamp is easily obtained by electroforming from IPS.

1 shows a schematic diagram of a stamp replication process by electroforming using IPS as a galvanic-template. The nickel stamp contains the same nanostructure as that of the original master stamp. Plasma enhanced CVD [see, eg, US Patent No. 5,244,730 for the field of semiconductor devices— "Plasma deposition of fluorocarbon"; US Patent No. 6184572-"Interlevel dielectric stack containing plasma deposited fluorinated amorphous carbon films for semiconductor devices"; And US Pat. No. 5698901-“Semiconductor device with amorphous carbon layer for reducing wiring delay”] that additional fluorocarbon films or other release layers should preferably be deposited on the IPS prior to the metalized seed layer. It should be stressed, otherwise the separation between the IPS and the electroformed nickel stamp will be difficult. This means that the stamp will undergo strong shear forces during separation. For example, Hong, S. et al (Microelectronics, Eng. Vol. 84, p. 977, 2007) describe hot embossing from nickel stamps electroformed in organic solvents that soften polymer films. The thermoplastic PVC film must be separated. As the patterned area is enlarged (eg, 3-4 inches), the surface area covered by the metal seed layer is relatively increased, which results in an increase in shear force upon separation. Thus, the increased shear force is sufficient to rupture the nanostructures of the polymer material to form the ruptured material, and there is a high risk that the ruptured material will fill in the cavity of the nanostructures on the nickel stamp. In such cases, an expensive and advanced cleaning method is needed to clean the stamp (eg, downstream plasma treatment).

If a stamp with a feature that is inverted for the features of the original master stamp is desired, a two step imprint process is performed. After the first imprint produces the IPS, the second imprint is performed on a substrate having a pre-coated imprint resist. The imprinted substrate is then used as a template for electroforming and a nickel stamp is obtained with the opposite features contrasted with the features of the original stamp.

A schematic of a stamp duplication process by a two step imprint process is shown in FIG. 2. Finally, by utilizing the Applicants' techniques, such as the IPS method for yield improvement and the combined thermal and UV nanoimprints disclosed in European patent, EP 1731962, precise pattern transfer with long range regularity over a large area is achieved. Casting was facilitated on the nickel stamp. However, one of the emphasis of the present inventors is that if there is no release layer, release is deposited on the imprinted substrate prior to metallization of the seed layer because the substrate resist is peeled off from the substrate and adhered strongly onto the electroformed Ni-stamp. The layer is important. To this end, this problem has been solved, for example, by adopting a release film that plasma-enhanced chemical vapor deposition (CVD) of a fluorocarbon film on an imprinted substrate prior to metallization of the seed layer. Because of this, only a simple cleaning method, such as electrochemical cathode cleaning and plasma etching, is required after the final electroformed nickel stamp has been formed.

Experiment Example

IPS from Ni Manufacturing process for stamp duplication

Example 1 Nickel Stamp with Photonic Crystal Structure (PSC)

For example, original master stamps were obtained by combined e-beam recording (EBR) and electroforming processes. The nickel stamp obtained in this manner consisted of an array of 230 nm wide PCS with a pitch of 450 nm and a depth of 130 nm over a 4-inch patterned area. The acrylate imprint resist was coated on a polycarbonate polymer sheet and then used as a substrate for nanoimprinting. After demolding the IPS, it was examined by AFM, SEM and optical microscope. The surface of the IPS was further modified by depositing a thin (˜6 nm) fluorocarbon film by plasma enhanced chemical vapor deposition. The nickel seed layer was then sputtered onto IPS prior to electroforming. The thickness of the sputtered Ni-seed layer was 10 nm. Since the inventors employed nickel as the seed layer, the definition of the nanostructures was kept excellent. It can be seen that the duplicated nickel-stamp has the same structure as that of the original master stamp, and the duplicated feature exhibits high fidelity as well as long range rules (FIG. 3).

Example 2: Nickel Stamp with Magnetic Storage Medium Structure

Original nickel imprints were produced by combined e-beam recording techniques and electroforming processes. In the data track area, the pattern had a width of 40 nm and a pitch of 120 nm. Imprinted IPS was examined by SEM using an acrylate imprint resist on a polycarbonate polymer sheet. Inverted nanofeatures were transferred with good accuracy. After sputtering nickel in a thin film (˜10 nm), electroforming was performed. Sputtering a thin metal layer instead of a thick layer is a great advantage because it has a high aspect ratio and prevents hole-inclusion due to narrow nanochannels with high pattern density. An electroformed nickel stamp was obtained having the same nanostructure as that of the original master stamp (FIG. 4).

Two steps From imprint Ni Manufacturing process for stamp duplication

Example 3: Nickel Stamp with Photonic Crystal Structure

The stamp consisted of an array of dots with a diameter of 200 nm and a pitch of 460 nm per 3-inch area. IPS comprising acrylate imprint resist on the polycarbonate carrier polymer sheet was imprinted onto the master stamp. In addition IPS was used to transfer the pattern onto the Si-wafer pre-coated with epoxy imprint resist. Finally, imprinted Si-wafers were used as templates for electroforming to obtain nickel stamp replicas containing structures that were inverse to the structure on the original stamp.

Example 4 Nickel Stamps with Magnetic Storage Media Nanostructures

In order to obtain an inverted nickel replica with a magnetic storage medium structure, the inventors followed the same procedure as in Example 3. The final nickel stamp having a structure complementary to that on the original stamp is shown in FIG. 6.

Claims (22)

A method for obtaining a metal stamp having the same structure as a master stamp from one or more intermediate stamps, the method comprising:
Providing a first imprint layer on top of the first carrier substrate;
Imprinting the structure in the first imprint layer using the master stamp to obtain a first intermediate stamp;
Providing a conductive layer on top of the structured first intermediate stamp to obtain a seed layer;
Plating a metal on top of the seed layer to obtain a metal stamp;
Separating the first intermediate stamp from the metal stamp. A method for obtaining a metal stamp having a structure inverse to the structure of a master stamp from two or more intermediate stamps,
Providing a second imprint layer on top of the second carrier layer;
Imprinting a structure in a second imprint layer using the first intermediate stamp to obtain a second intermediate stamp;
Providing a conductive layer on top of the second intermediate stamp to obtain a seed layer;
Plating a metal on top of the seed layer to obtain a metal stamp;
Separating the second intermediate stamp from the metal stamp. 3. The method of claim 1 or 2, wherein the first and second carrier substrates comprise a polymeric material. The method of claim 1, further comprising providing an anti-tacky molecule in the resist prior to obtaining the seed layer. The method of claim 1 wherein the first carrier substrate comprises a transparent material. The method of claim 2, wherein the second carrier substrate comprises a transparent or opaque material. 7. The method of any one of claims 1, 2, 5 or 6, wherein the carrier substrate comprises glass, semiconductor material or metal. The method of claim 1 or 2, wherein the first and second imprint layers are coated on top of the carrier substrate. The method of claim 1, wherein the seed layer is sputtered on top of the structure in the first intermediate stamp. The method of claim 1, wherein the seed layer is sputtered on top of the structure in the second intermediate stamp. The method of claim 1, wherein the seed layer is at least monoatomic conductive layer thick. The method of claim 11, wherein the seed layer comprises a conductive material. The method of claim 12 wherein the conductive material comprises a metal. The method of claim 13, wherein the metal consists of at least one of nickel, gold, silver, titanium, copper, and aluminum. The method of claim 1, wherein the metal stamp is electroplated on top of the conductive layer. The method of claim 1, wherein the first imprint layer material comprises a conductive polymer. The method of claim 2, wherein the second imprint layer material comprises a conductive polymer. 18. The method of claim 17, wherein the metal stamp is electroplated on top of the conductive polymer. 19. The method of any one of claims 1 to 18, wherein separation between the intermediate stamp and the metal stamp is achieved by mechanical demolding. 20. The process according to any one of the preceding claims, carried out at a constant temperature in the range of 15 to 100 ° C, preferably 20 to 70 ° C. 21. The method of any of claims 1-20, wherein the structure imprinted within the imprint layer comprises micro and nano structures. 22. The method of any one of the preceding claims, wherein the structure has a size greater than 5 nm.

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