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Title:
METHOD OF IMPRINT LITHOGRAPHY OF CONDUCTIVE MATERIALS; STAMP FOR IMPRINT LITHOGRAPHY, AND APPARATUS FOR IMPRINT LITHOGRAPH
Document Type and Number:
WIPO Patent Application WO/2018/026378
Kind Code:
A1
Abstract:
A method of patterning with imprint lithography, a stamp for imprint lithography, an imprint roller of a roll-to-roll substrate processing apparatus, and a substrate processing apparatus are described. The method includes providing a layer of a conductive paste on a substrate, wherein the conductive paste has a viscosity of 0.3 Pa.s or above, particularly of 1.5 Pa.s or above; imprinting a stamp in the layer of the conductive paste to generate a patterned layer of the conductive paste; fully or partially curing the patterned layer; and releasing the stamp from the patterned layer.

Inventors:
VISSER ROBERT JAN (US)
CUNNINGHAM KEVIN L (US)
Application Number:
PCT/US2016/045769
Publication Date:
February 08, 2018
Filing Date:
August 05, 2016
Export Citation:
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Assignee:
APPLIED MATERIALS INC (US)
International Classes:
H01L21/027; G03F7/00; G03F9/00
Foreign References:
US20150037922A12015-02-05
US20090046362A12009-02-19
KR20090061771A2009-06-17
US20070298176A12007-12-27
KR20100133136A2010-12-21
Attorney, Agent or Firm:
PATTERSON, B. Todd et al. (US)
Download PDF:
Claims:
CLAIMS

1. A method of patterning with imprint lithography, comprising: providing a layer of a conductive paste on a substrate, wherein the conductive paste has a viscosity of 1.5 Pa-s or above; imprinting a stamp in the layer of the conductive paste to generate a patterned layer of the conductive paste; j fully or partially curing the patterned layer; and releasing the stamp from the patterned layer.

2. The method according to claim 1, wherein the conductive paste has a viscosity of 100 Pa-s or above.

3. The method according to any of claims 1 to 2, wherein the stamp has a plurality of features for generating the pattern, and wherein at least 10% of the features have a feature depth larger than a thickness of the layer of the conductive paste.

4. The method according claim 3, wherein the feature depth provides for a hollow spaces between the conductive paste and the stamp.

5. The method according to any of claims 3 to 4, wherein at least 10% of the features each have an opening configured for reducing a gas pressure of a gas generated by the fully or partially curing of the patterned layer.

6. The method according to claim 4, wherein openings configured for reducing a gas pressure in the hollow spaces are provided.

7. The method according to any of claims 1 to 6, wherein the gas pressure generates a force assisting the releasing of the stamp from the patterned layer.

8. A stamp for imprint lithography, comprising: a base body; and a plurality of features for generating a pattern upon imprinting the stamp in a layer, wherein the plurality of features are supported by the base body, wherein at least 10% of the plurality features have a feature width W and a feature depth D providing a ratio of D/W of 1.5 or larger, particularly of 5 or lager, for generating of hollow spaces during imprint lithography.

9. The stamp according to claim 8, further comprising: a plurality of openings in the base body configured to enable gas flow out off or into the hollow spaces.

10. The stamp according to any of claims 8 to 9, wherein the plurality of features comprises: side surfaces, bottom surfaces and top surfaces, and wherein at least one of the side surfaces, the bottom surfaces and top surfaces are coated with a coating.

11. An imprint roller of a roll-to-roll substrate processing apparatus, comprising: a stamp according to any of claims 8 to 10, wherein the plurality of features are provided on a surface of the imprint roller.

12. A substrate processing apparatus, comprising: a stamp according to any of claims 8 to 10.

13. The substrate processing apparatus according to claim 12, wherein the stamp is provided on a surface of a roller configured for roll-to-roll processing

14. The substrate processing apparatus according to any of claims 12 to 13, further comprising: a curing unit select from the group consisting of a light emission unit and a heating unit configured for curing the layer while imprinting the stamp in the layer.

Description:
METHOD OF IMPRINT LITHOGRAPHY OF CONDUCTIVE MATERIALS; STAMP FOR IMPRINT LITHOGRAPHY, AND APPARATUS FOR IMPRINT

LITHOGRAPH

TECHNICAL FIELD

[0001] Embodiments of the present disclosure relate to imprint lithography, particularly of imprint lithography of conductive materials. Embodiments of the present disclosure particularly relate to imprint lithography of conductive pastes, a stamp for imprint lithography, and an apparatus utilizing the method and an apparatus utilizing the stamp.

BACKGROUND

[0002] Patterning of thin films is desired for the plurality of applications, for example manufacturing of microelectronic devices, optoelectronic devices, or optical devices. Optical lithography techniques may be used for patterning thin films in a device. However, optical lithography techniques may be expensive and/or may reach their limits particularly on substrates having larger sizes.

[0003] Particularly for roll-to-roll processing, there is a limitation in manufacturing of small feature sizes using conventional techniques without the use of expensive photolithography. Printing techniques such as screen print, gravure, flexographic, Inkjet, etc., are for example limited to feature sizes, e.g. > 10 μπι, which may not be sufficiently small.

[0004] In addition, sheet-to-sheet processes can benefit from imprint lithography processes. Imprint lithography may provide for a comparably inexpensive process for patterning a thin film in order to provide a patterned structure in a device.

[0005] Conductive features, i.e. features manufactured from a conductive material, may be utilized for electronic devices, microelectronic devices, optoelectronic devices, and optical devices. [0006] An improvement for manufacturing conductive features is beneficial.

SUMMARY

[0007] In light of the above, a method of patterning with imprint lithography, a stamp for imprint lithography, an imprint roller of a roll-to-roll substrate processing apparatus, and a substrate processing apparatus are provided. Further aspects, advantages, and features of the present disclosure are apparent from the dependent claims, the description, and the accompanying drawings.

[0008] According to one embodiment, a method of patterning with imprint lithography is provided. The method includes providing a layer of a conductive paste on a substrate, wherein the conductive paste has a viscosity of 0.3 Pa -s or above, particularly of 1.5 Pa-s or above; imprinting a stamp in the layer of the conductive paste to generate a patterned layer of the conductive paste; fully or partially curing the patterned layer; and releasing the stamp from the patterned layer.

[0009] According to further embodiment, a stamp for imprint lithography is provided. The stamp includes a base body; and a plurality of features for generating a pattern upon imprinting the stamp in a layer, wherein the plurality of features are supported by the base body, wherein at least 10% of the plurality features have a feature width W and a feature depth D providing a ratio of D/W of 1.5 or larger, particularly of 5 or lager, for generating of hollow spaces during imprint lithography.

[0010] According to a further embodiment, an imprint roller of a roll-to-roll substrate processing apparatus is provided. The imprint roller includes a stamp. The stamp includes a base body; and a plurality of features for generating a pattern upon imprinting the stamp in a layer, wherein the plurality of features are supported by the base body, wherein at least 10% of the plurality features have a feature width W and a feature depth D providing a ratio of D/W of 1.5 or larger, particularly of 5 or lager, for generating of hollow spaces during imprint lithography, and wherein the plurality of features are provided on a surface of the roller.

[0011] According to a further embodiment, a substrate processing apparatus is provided. The apparatus includes a stamp. The stamp includes a base body; and a plurality of features for generating a pattern upon imprinting the stamp in a layer, wherein the plurality of features are supported by the base body, wherein at least 10% of the plurality features have a feature width W and a feature depth D providing a ratio of D/W of 1.5 or larger, particularly of 5 or lager, for generating of hollow spaces during imprint lithography.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Embodiments of the present disclosure, briefly summarized above and discussed in greater detail below, can be understood by reference to the illustrative embodiments of the disclosure depicted in the appended drawings. However, the appended drawings illustrate only typical embodiments of the disclosure and are therefore not to be considered limiting of scope, for the disclosure may admit to other equally effective embodiments.

[0013] FIGS. 1A and IB illustrate a process of imprint lithography of a thin film on the substrate according to embodiments of the present disclosure and utilizing a stamp for imprint lithography according to the present disclosure;

[0014] FIG. 2 shows a stamp for imprint lithography according to the present disclosure;

[0015] FIG. 3 shows a further stamp for imprint lithography according to the present disclosure;

[0016] FIGS. 4A and 4B illustrate the process of imprint lithography of thin film on a substrate according to embodiments of the present disclosure;

[0017] FIG. 5 is a schematic drawing of an apparatus for providing a pattern in a metal paste layer as used in embodiments described herein; and

[0018] FIG. 6 shows a flowchart for illustrating a method of imprint lithography.

[0019] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.

DETAILED DESCRIPTION OF EMBODIMENTS

[0020] Embodiments of the present disclosure provide a method of patterning with imprint lithography. The method includes providing a layer of a conductive paste on a substrate, wherein the conductive paste has a viscosity of 1.5 Pa-s or above, imprinting a stamp in the layer of the conductive paste to generate a patterned layer of the conductive paste, fully or partially curing the patterned layer, and releasing the stamp from the patterned layer. Embodiments of the present disclosure further provide and/or utilize a stamp for imprint lithography. The stamp includes a base body, and a plurality of features for generating a pattern upon imprinting the stamp in a layer, wherein the plurality of features are supported by the base body, wherein at least 10% of the plurality features have a feature width W and a feature depth D providing a ratio of D/W of 1.5 or larger, particularly 5 or larger, for generating of hollow spaces during imprint lithography.

[0021] Role-to-roll (R2R) imprint lithography can achieve feature sizes with a resolution of about 1 μπι or below, e.g. even sub- micro resolution. Accordingly, embodiments according to the present disclosure, which utilize imprint lithography, may enable fabrication of small features on flexible substrates.

[0022] There are two modes for utilizing imprint of geography. A film can be deposited and imprinted. The imprinted material can act as an etch mask for a subsequent etching. Alternatively, a film can be deposited and imprinted. The imprinted material, for example a resist material, can be a permanent part of the product and forms a deposited film. Imprint lithography, which can be utilized for embodiments of the present disclosure, patterned films into a desired or predetermined shape by imprinting a material layer with a stamp.

[0023] According to embodiments described in the present disclosure, imprint lithography may be in particular beneficial for R2R processes. R2R processes allow for a high productivity when depositing films, and manufacturing patterned films. For example, films, such as thin films, i.e. material layers having a thickness of a few nanometers to several tens of microns, can be deposited and patterned in a R2R process. The thin film can be provided on plastic substrates like PET, PEN, COP, PI, TAC (Triacetyl cellulose) and other similar substrates.

[0024] According to further embodiments of the present disclosure, depositing and patterning of thin films may also be applied for metal or thin glass substrates like Coming's Willow Glass. For example, thin films can be manufactured in a sheet-to-sheet process. This may apply to glass substrates or plastic substrates adhered to a glass carrier. Further embodiments may be directed to metal substrates, organic substrates, glass composite substrates, e.g. used in printed circuit board (PCB) manufacturing, ABF (Ajinomoto build-up films), , e.g. used in integrated circuit (IC) packaging, and other rigid substrates.

[0025] FIGS. 1A and IB show a method of patterning with imprint lithography and the stamp 110 utilized for imprint lithography. A layer 102 of a conductive paste is provided on a substrate 100. According to embodiments of the present disclosure, the conductive paste has a viscosity of 1.5 Pa-s or above. According to some embodiments of the present disclosure, which can be combined with other embodiments described herein, the conductive paste can be a couple paste or a silver paste.

[0026] A stamp 110 is imprinted in the layer 102 of the conductive paste to generate a pattern in the patterned layer 104 as shown in fig. IB. The stamp 110 includes a base body 1 12 and a plurality of features 114. The features of the stamp can, for example, be formed by recesses in the stamp 1 10, wherein recesses in the stamp result in protrusions in the patterned layer 104. A protrusion in the patterned layer corresponding to a feature of the stamp can be referred to as a pattern feature.

[0027] Each feature 114 of the stamp 110 has a feature width W and a feature depth D. A feature of the stamp is formed by a bottom surface 121, side surfaces 123, and one or more adjacent top surfaces 122. Exemplarily, fig. 1A shows a cross-section of a stamp 1 10, wherein the feature width W is shown. According to embodiments of the present disclosure, a feature also has a second feature with W' in a direction not parallel to the paper plane of fig. 1A, for example in a direction perpendicular to the feature width W shown in fig. 1A.

[0028] According to embodiments of the present disclosure, a plurality of features can be provided, wherein the plurality of features comprises: side surfaces, bottom surfaces and top surfaces. For example, each feature can include one or more side surfaces, a bottom surface and can be surrounded by top surfaces. A multi-level stamp may further include a more than one bottom surface. According to some embodiments, which can be combined with other embodiments described herein, at least one of the side surfaces, the bottom surfaces and top surfaces are coated with a coating.

[0029] According to some embodiments, a plurality of features 1 14 of the stamp 1 10 can have the same feature width and the same feature depth. Additionally or alternatively, different features of the stamp may have different feature geometries, i.e. different feature widths and different feature depths. Yet further, two or more features with different sizes may be placed next to each other in a repeating manner to form a repeating pattern.

[0030] According to some embodiments of the present disclosure, the pattern features can be selected from the group consisting of: a line, a pole, a trench, a hole, a circle, a square, a rectangle, a triangle, other polygons, a pyramid, plateaus, and combinations or arrays thereof. Generally, the pattern features may include shapes, which are used in circuit fabrication. The features of the stamp can have corresponding geometries, wherein a protrusion corresponds to a recess and vice versa. The pattern features may comprise a mask for the fabrication of conducting lines in a circuit.

[0031] According to some embodiments of the present disclosure, methods of patterning with imprint lithography can be utilized for manufacturing of wire grid polarizers, wherein for example lines are provided as the pattern feature. For example, lines can have a half page of 100 nm or below, for example 50 nm to 100 nm.

[0032] As shown in fig. I B, the stamp 1 10 and the substrate 100 are removed with respect to each other such that the layer 102 of the conductive paste is imprinted to form a patterned layer 104. For example, the stamp 1 10 may be lowered on to the substrate, i.e. moved relative to the substrate. Alternatively, the substrate 100 may be moved relative to the stamp 1 10. According to yet further alternative, both the substrate 100 and the stamp 1 10 may be moved for imprinting the stamp 1 10 into the layer 102 of the conductive material.

[0033] According to some embodiments of the present disclosure, as exemplarily described with respect to fig. 5, the stamp 110 can be a portion of an imprint roller or the stamp can be attached to a roller, wherein imprinting can be conducted in an R2R process. For imprint lithography in an R2R process, a roller may rotate around the rotation axis and the substrate is moved over the surface of the rotor, for example a cylindrical surface. For example, the substrate transport velocity v can correspond to the angular velocity w of the roller according to the formula v = r-w, wherein R is the radius of the roller. That is, the substrate transport velocity is similar to the cross-radial velocity, i.e. the tangential velocity, of the roller.

[0034] According to some embodiments of the present disclosure, the imprint lithography process may also be a self-aligned imprint lithography (SAIL) process. For a SAIL process, i.e. a multi-level imprint lithography process, a recess in the stamp can have two or more features depths of different portions of the feature. This can be very efficient for generating a pattern in a thin film. Accordingly, a SAIL process includes a multi-level stamp. Manufacturing of lines such as, connection lines with an imprint lithography process, e.g. a SAIL process, allows for lines having a small width and small distances between the lines.

[0035] According to embodiments of the present disclosure and as exemplarily illustrated with respect to FIGS. 1A and IB, the conductive paste is provided on the substrate 100 to form a layer 102. The conductive paste is imprinted with a stamp 1 10, which forms the desired structure. The conductive material is cured, for example by light, such as UV light, heat. The curing may be fully or partially be provided before the imprint stamp is separated or released from the substrate. For example, the curing may not be complete, but provide enough structural stability so that the imprinting stamp can release the paste without damaging the imprinted structures. [0036] The conductive material may receive subsequent curing to fully cure the conductive material. In the event residual material may be left on the substrate at a portion of the stamp 110 corresponding to one or more of the top surfaces 122 of the stamp, an etching process can be provided to remove the residual material. For example a light etch can be provided to remove procedural conductive paste material in between pattern structures. This etch can be a wet etch or dry etch.

[0037] The embodiments described herein referred to a patterned layer on the substrate, which is directly imprinted by the stamp. That is, the patterned layer forms a permanent part of the product and forms a deposited film, which will be part of the layer stack of the manufactured device. According to embodiments of the present disclosure, the patterned layer 104 forms of functional layer in a device. The conductive paste is cured to form conductive structures of the device, which will for example not be removed after etch process.

[0038] According to another aspect of the present disclosure, the hollow space 214 may allow for thinning the residual layer of photoresist or conductive paste material left at portions of the stamp corresponding to one or more top surfaces 122 of the stamp. In comparison, a stamp that does not have a feature depth sufficiently large to provide a hollow space to accommodate both the air that will be displaced as the stamp imprints the conductive paste and e.g. the gas that may evolv, will result in excess residual material in the event the layer 102 of conductive paste is likely to thick. A stamp according to the present disclosure results in the reduction or even avoiding of receipt will materials on the substrate.

[0039] Fig. 2 shows another embodiment illustrating a stamp 1 10 according to embodiments of the present disclosure. The stamp 1 10 includes a base body 112 and features 114. The features have a width W (and a further width W not shown in one cross-section, i.e. in fig. 2) and a depth D. As shown in fig. 2, the stamp 110 may have features with a depth D, which is sufficiently large to provide a hollow space 214 between a bottom surface 121 of the feature 1 14 of the stamp 1 10 and a surface 221 of the patterned layer 104. [0040] One aspect of the process of imprint lithography with conductive pastes is that the conductive paste will evolve gas during the curing process (partial or full curing). The hollow space 214 provided by the depth of the features 114 of the stamp 110 result in an imprint lithography, wherein the material is not fully filling the feature in the stamp. Accordingly, the gas has a volume, in which to evolve.

[0041] The amount of gas, which may evolve from the conductive paste, can be adjusted by at least one of: the viscosity of the conductive paste, the boiling temperature of materials within the conductive paste, the volume of the hollow space, the degree of curing, further structural features of the stamp (see for example fig. 3), and combinations thereof.

[0042] For example, materials can be added to the conductive paste, which can increase or reduce the viscosity. This can result in an adjustment of the curing time that can or will be provided before release of the stamp. A low boiling temperature solvent may be added to the resist, e.g. one may titrate a low boiling solvent to the resist, to increase the gas amount evolving during curing. An increase of the volume of the hollow space 214 can increase the time until a pressure builds up in the hollow space, which may counteract evolving of gas. Yet further, as shown in fig. 3, features 114 may have openings 314 perforations to allow gas to escape from the stamp. As a yet further example, curing may take place under vacuum conditions, for example a technical vacuum, which may further influence the gas pressure in the hollow space, particularly with the presence of openings or perforations.

[0043] According to embodiments of the present disclosure, evolved gas is used as a way to encourage release of the stamp. For example, there will be some interplay between (1) the time that the evolved gas forces release, and (2) the degree of curing at that moment of the release. Further aspects, which may interplay to influence encouraging release of the stamp are mentioned above and be at least one element selected from the group consisting of: the viscosity of the conductive paste, the boiling temperature of materials within the conductive paste, the volume of the hollow space, the degree of curing, further structural features of the stamp (see for example fig. 3), and combinations thereof. [0044] Fig. 2 exemplarily illustrate embodiments of the stamp 1 10 having features 1 14, wherein the depth of the features are provided to have a hollow space 214 when imprinting the stamp in the layer 102 of the conductive paste. Accordingly, a stamp is provided. The stamp includes a base body and a plurality of features for generating a pattern upon imprinting the stamp in a layer, wherein the plurality of features are supported by the base body, wherein at least 10% of the plurality features have a feature width W and a feature depth D providing a ratio of D/W of 5 or larger for generating of hollow spaces during imprint lithography. According to yet further embodiments of the present disclosure, which can be combined with other embodiments described herein, a pattern of conductive material provided with imprint lithography as described herein, can be subject to a further manufacturing process of electroplating. The electroplating will grow or deposit further conductive material on the features of the pattern. Accordingly, the patterned layer manufactured with imprint lithography can be a seed layer for a further manufacturing process.

[0045] As described herein, the feature width in one direction is the maximum dimension in this direction. Similarly, the feature depth if the maximum depth of the feature. For multi-level stamp designs, one feature may have two or more width in the same direction and two or more depths. For example, the width of a cylindrical feature will typically be the diameter and the depth of the cylindrical feature will typically be the height of the respective cylinder. As a further example, for rectangular features widths and the height may typically be provided by the dimensions of the corresponding rectangular cuboid.

[0046] Fig. 3 illustrates a further example of a stamp 1 10 according to embodiments of the present disclosure. Fig. 3 illustrates a patterned layer 104 on the substrate 100 after the stamp 1 10 has been imprinted in the conductive paste. The depth of the features in the stamp 1 10 is sufficiently large to have a hollow space 214 between the surface of the patterned layer 104 and a button surface of the feature. According to some embodiments of the present disclosure, which can be combined with other embodiments described herein, the hollow space 214 can be in fluid communication with another area through openings 314. For example, opening 314 can be perforations, particularly in a base body of the stamp 1 10. According to embodiments of the present disclosure, the openings, e.g. a plurality of openings in the base body, can be configured to enable gas flow out off or into the hollow spaces.

[0047] The openings 314 or perforations allow for the release of the gas evolved from the conductive paste up on curing. According to some embodiments, the openings 314 can extend through the base body of the stamp 1 10. Accordingly, the openings can provide a fluid communication between the hollow space 214 and an area outside of the stamp 110. For example, for a patterning conducted under technical vacuum, the area outside of the stamp may have a pressure of 10 mbar or below, or 1 mbar or below.

[0048] According to some embodiments, the size of the opening 314 (or perforations) can be in a range of 50 μηι to 500 μιη. According to yet further embodiments, two or more opening 314, which are in fluid communication with a respective hollow space 214 of the feature, may open out into a common channel or a common further hollow space, particularly a further hollow space having a volume at least 100 times larger (or even 10000 times) larger than a volume of a hollow space 214 of a feature.

[0049] As described above, there are a plurality of options to influence the evolving of gas from the conductive paste, which occurs during curing or pre-curing of the imprinted layer during an imprint lithography process. These options can be combined with other options to allow for an adjustment of an outgassing of the conductive paste in order to provide a desired patterned layer, e.g. with respect to feature shape, material composition, or the like. Further, as illustrated with respect to figures 4A and 4B, the options can additionally or alternatively be combined to allow assisting the release of the stamp from the substrate.

[0050] Fig. 4A shows a stamp 1 10 having a base body 1 12. The stamp 110 is partially imprinted in a layer of a conductive paste to generate a patterned layer 104. For example, the patterned layer 104 can be provided on the substrate. According to some embodiments, which can be combined with other embodiments described herein, a layer of conductive paste or a patterned layer can be provided on a substrate or over a substrate. Particularly the layer can be provided in direct contact with the substrate or one or more further layers can be provided between the substrate and a layer of conductive paste (resulting in a patterned layer of a device.) [0051] As shown in fig. 4A, a hollow space 214 is provided over the patterned layer 104. The recess of the feature of the stamp is not fully filled with the conductive paste. Fig. 4A shows a situation having small space between top surfaces of the stamp and the substrate. Fig. 4B shows a situation, for which the stamp 110 having a base body 112 is fully imprinted in the conductive paste. Top surfaces of the stamp are in contact with the structure or layer below the conductive paste, for example a substrate 100 as shown in fig. 4B. In addition, the situation shown in fig. 4B has a hollow space 214 between the conductive paste and the stamp 110. The hollow space 214 allows for evolving of gas from the conductive paste into the hollow space. Evolving of the gas increases the pressure in the hollow space 214. For example, the pressure caused by the evolution of gas from the conductive paste increases in hollow spaces of at least 10% of the features of the stamp, particularly at least 50% of the features of the stamp, even more particularly at least 90% of the features of the stamp. The pressure in the hollow space results in a force as indicated by arrow 402, which may assist releasing or which may release the stamp 110 from the substrate 100.

[0052] According to embodiments of the present disclosure, the pressure and, thus, a force acting in a release direction of releasing the stamp from the substrate can be increased by reducing the volume of the hollow spaces, reducing the viscosity of the conductive paste, increasing the curing time, adding low boiling temperature solvents to the conductive paste, reducing the size of perforations (or not providing perforations), or combinations thereof. According to embodiments of the present disclosure, the pressure, and thus, a force acting in the release direction of releasing the stamp from the substrate can be reduced by increasing the volume of the hollow space, increasing the viscosity of the conductive paste, reducing the curing time, reducing the content of low boiling temperature solvents in the conductive paste, increasing the size of perforations (or providing perforations), or combinations thereof. Light of the above, embodiments of the present disclosure allow for providing a predefined or desired release force to act on the stamp for an improved imprint lithography process.

[0053] Further details of an imprint lithography process, for example SAIL process, which can additionally or alternatively be provided are shown exemplarily in FIG. 5. According to embodiments described herein, which can be combined with other embodiments described herein, the method of imprint lithography and the stamp for imprint lithography can be included and/or utilized in a roll-to-roll process (R2R process) . An imprint station can include a roller 510, which can rotate around the axis 514 of the roller 510. Fig. 5 illustrates the rotation by arrow 512. Upon rotation of the roller 510, a pattern of a stamp 1 10 attached to the roller or being a portion of the roller is imprinted in a layerl 02 of conductive paste.

[0054] As shown in FIG. 5, the roller 510 has a stamp 1 10 provided thereon or being a portion of the roller. When the substrate 100 is moved through the gap between the roller 510 and, for example, another roller 502, a pattern of the stamp 1 10 is embossed in the layer 102. This results in the patterned layer 104. The arrow 503 indicates a rotation of the other roller 502 around the axis 504 of the other roller 502. The arrow 101 in FIG. 5 indicates the movement of the substrate 100 through the gap between the roller 510 and the roller 502. The rollers rotate as indicated by the arrows 5012 and 503. For example, according to some embodiments of the present disclosure, the substrate transport velocity along arrow 101 is similar to the cross-radial velocities, i.e. the tangential velocities, of the rollers.

[0055] According to embodiments of the present disclosure, and R2R apparatus can be provided with imprint lithography, wherein imprint photography is conducted with conductive paste, particularly wherein the conductive paste is a functional layer in a device to be manufactured. Before imprinting or embossing a stamp or an imprint roller in a layer of conductive paste, the conductive paste is provided on or over the substrate.

[0056] Fig. 5 shows a deposition unit 544 for applying the conductive paste onto or over the substrate 100. Applying the conductive paste provides for the layer 102 of conductive material. For example, one or more deposition units 544 can coat the layer 102 using meniscus coating, slot die coating, doctor blade coating, gravure coating, flexographic coating, spray coating. After the layer 102 of the conductive paste has been deposited, a stamp 1 10 is used to emboss the pattern in the layer 102 to generate a patterned layer 104.

[0057] According to some embodiments of the present disclosure, which can be combined with other embodiments of the present disclosure, the imprinted conductive paste is cured with curing unit 532. The curing unit 532 can be selected from the group consisting of a light emission unit and a heating unit configured for curing the layer while imprinting the stamp in the layer, wherein emission 533 is generated. For example, the light emission unit can emit UV light, particularly in the wavelength range from 410 nm to 190 nm. Another example the emission unit can emit IR light, particularly in the wavelength range from 9-1 1 micrometers (CO2 laser). Another example the emission unit can emit broadband light from the IR to the UV with emission particularly in the wavelength range from 3 micrometers to 250nm. This emission may be filtered to select only a portion of the blackbody emission using optical filters.

[0058] According to yet further embodiments, which can be combined with other embodiments described herein, optionally also an optical measurement unit for evaluating the result of the substrate processing can be provided.

[0059] Fig. 5 shows a curing unit 532. The curing unit 532 is configured to partially or fully cure the conductive paste while the stamp 110 is imprinted into the layer of conductive paste. According to embodiments of the present disclosure, the degree of curing can be adjusted by the intensity of the curing unit, for example the light intensity or the heat emission intensity. Additionally or alternatively, the degree of curing can be adjusted by the rotational speed of the roller 510 and the substrate 100.

[0060] In the event of partial curing by the curing unit 532, a second curing unit 534 can be provided downstream of the curing unit 532, wherein second emission 535 is generated. The second curing unit 534 can fully cure the partially cured patterned layer 104.

[0061] According to embodiments of the present disclosure, conductive paste is imprinted with imprint lithography. The imprinted material, for example a resist material, can be a permanent part of the product and forms a deposited film. The embodiments described herein referred to a patterned layer on the substrate, which is directly imprinted by the stamp. That is, the patterned layer forms a permanent part of the product and forms a deposited film, which will be part of the layer stack of the manufactured device. According to embodiments of the present disclosure, the patterned layer 104 forms of functional layer in a device. [0062] Fig. 6 shows a flowchart of a method of patterning with imprint lithography according to embodiments of the present disclosure. As illustrated by box 602, a layer of a conductive paste is provided. The conductive paste has a viscosity of 0.3 Pa -s or above. The conductive paste is configured to form a functional layer in a device to be manufactured by the method. As illustrated by box 604 the method includes imprinting or embossing a stamp in the layer of the conductive paste to generate a patterned layer of the conductive paste. Box 606 further illustrates fully or partially curing the patterned layer. According to some embodiments of the present disclosure, which can be combined with other embodiments of the present disclosure, the stamp is released from the patterned layer, wherein particularly a pressure of a gas evolved from the conductive paste during curing into a hollow space of a feature of the stamp can assist releasing the stamp or may release the stamp from the patterned layer of the substrate, respectively. According to yet further embodiments, which can be combined with other embodiments described herein, box 604 may include imprinting or embossing a stamp in a layer of the conductive paste, partially curing the conductive paste, and releasing the stamp from the layer of the conductive paste.

[0063] Embodiments of the present disclosure have several advantages including: imprinting with imprint lithography a conductive paste, which forms for example a functional layer of a device, wherein small feature sizes can be provided; allowing gas to evolve from the conductive paste during curing of a patterned layer by providing a feature depth considering for a hollow space; designing the hollow space and/or openings in fluid communication with the hollow space to allow for increase or decrease, particularly for adjustment and/or control, of the pressure of the gas evolved in the hollow space; providing for a stamp release force or a force assisting in stamp release due to the pressure in the hollow space; reducing residual material of the patterned layer after curing; enabling patterning of conductive material with a high aspect ratio; enabling fabrication of small features on flexible substrates, particularly with high productivity; and/or enabling fabrication of self-aligned conductive layers.

[0064] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.