阅读说明：本技术 非平面图案化纳米结构表面及用于其制造的印刷方法 (Non-planar patterned nanostructured surfaces and printing methods for their fabrication ) 是由 詹姆斯·朱 卡尔·K·斯腾斯瓦德 丹尼尔·M·伦茨 托马斯·J·梅茨勒 莫塞斯·M·大卫 于 2018-12-26 设计创作，主要内容包括：本发明提供了一种将图案施加到非平面表面的方法。印模具有主表面,所述主表面具有横向尺寸大于0且小于约5微米的图案元件。所述印模的所述主表面具有官能化分子,所述官能化分子具有被选择用于化学键合到所述非平面表面的官能团。所述印模被定位成引起与所述非平面表面的滚动接触,并且接触所述非平面表面以在其上形成所述官能化材料的自组装单层(SAM),并且向所述非平面表面赋予图案元件的布置。所述印模的所述主表面相对于所述非平面表面平移,使得：控制在所述压印表面与所述非平面表面之间的界面处的接触力,并且在所述压印表面和所述非平面表面彼此接触时,允许所述界面处的接触压力变化。(The present invention provides a method of applying a pattern to a non-planar surface. The stamp has a major surface with pattern elements having a lateral dimension greater than 0 and less than about 5 microns. The major surface of the stamp has functionalizing molecules having functional groups selected for chemical bonding to the non-planar surface. The stamp is positioned to cause rolling contact with the non-planar surface and contacts the non-planar surface to form a self-assembled monolayer (SAM) of the functionalized material thereon and to impart an arrangement of pattern elements to the non-planar surface. The major surface of the stamp is translated relative to the non-planar surface such that: controlling a contact force at an interface between the stamping surface and the non-planar surface, and allowing a contact pressure at the interface to vary when the stamping surface and the non-planar surface are in contact with each other.)

1. A method of applying a pattern to a non-planar surface, wherein at least a portion of the non-planar surface has a radius of curvature, the method comprising:

providing a stamp having a major surface comprising a relief pattern of pattern elements extending away from a base surface, wherein each pattern element comprises a stamping surface having a lateral dimension greater than 0 and less than about 5 microns, and wherein the stamping surface comprises an ink having functionalized molecules with functional groups chemically bonded to the non-planar surface;

positioning the stamp to cause rolling contact between the non-planar surface and the major surface of the stamp;

contacting the stamping surface of the pattern elements with the non-planar surface to form a self-assembled monolayer (SAM) of the functionalizing molecules on the non-planar surface and to impart an arrangement of pattern elements to the non-planar surface; and

translating the major surface of the stamp relative to the non-planar surface, wherein translating the major surface of the stamp comprises:

(1) controlling a contact force at an interface between the stamping surface and the non-planar surface, an

(2) Allowing a contact pressure at the interface to vary when the stamping surface and the non-planar surface are in contact with each other.

2. The method of claim 1, wherein a substantially constant contact force is maintained at the interface.

3. The method of claim 1, wherein the contact force is varied to maintain a predetermined value of contact force at the interface as the stamping surface moves over the non-planar surface.

4. The method of claim 1, wherein the stamp comprises an elastomeric material.

5. The method of claim 1, wherein the contact force varies according to a predetermined contact force profile.

6. The method of claim 1, further comprising repositioning the stamp in a step-and-repeat manner to apply the arrangement of pattern elements to a plurality of different portions of the non-planar surface.

7. The method of claim 1, wherein the stamping surface comprises poly (dimethylsiloxane) (PDMS), and wherein the functionalizing molecule is an organosulfur compound selected from the group consisting of alkyl thiols, aryl thiols, and combinations thereof.

8. The method of claim 1, wherein the non-planar surface is a metal selected from the group consisting of gold, silver, platinum, palladium, copper, and alloys and combinations thereof.

9. An apparatus for applying a pattern to a non-planar surface having at least one portion with a radius of curvature, the apparatus comprising:

a stamp comprising an elastomeric stamp having a first major surface, wherein the first major surface of the stamp has a relief pattern of pattern elements extending away from a base surface, and wherein each pattern element comprises a stamping surface having a lateral dimension of greater than 0 and less than about 5 microns,

an ink absorbed into the stamping surface, the ink comprising a functionalizing molecule having a functional group that chemically bonds to the non-planar surface;

a first motion controller supporting the stamp and adapted to move the stamp relative to the non-planar surface;

a second motion controller adapted to move the non-planar surface; and

a force controller to control a force at an interface between the stamping surface and the non-planar surface on the stamp; wherein

The first and second motion controllers move the stamp and the non-planar surface in a relative motion such that the stamping surface contacts the non-planar surface to impart an arrangement of pattern elements to the non-planar surface, and wherein the relative motion between the stamp and the non-planar surface is regulated by the force controller to:

(1) controlling a contact force at an interface between the stamping surface and the non-planar surface, an

(2) Allowing a contact pressure at the interface to vary when the stamping surface and the non-planar surface are in contact with each other.

10. The apparatus of claim 9, wherein the non-planar surface is an outer surface of a roller.

11. A method of applying a pattern to an outer surface of a roller, the method comprising:

imbibing an ink into a major surface of a stamp, the ink comprising a functionalizing molecule having a functional group selected for chemical bonding to the outer surface of the roller, wherein the major surface of the stamp comprises a relief pattern of pattern elements extending away from a base surface, and wherein each pattern element comprises a stamping surface having a lateral dimension greater than 0 and less than about 5 microns;

contacting the stamping surface of the pattern elements with the surface of the roller to bond the functional groups to the surface of the roller to form a self-assembled monolayer (SAM) of the functionalized molecules on the surface of the roller and to impart an arrangement of pattern elements to the surface of the roller;

translating the major surface of the stamp relative to the surface of the roller, wherein translating the major surface of the stamp comprises:

(1) controlling a contact force at an interface between a patterned surface and the surface of the roller, an

(2) Allowing a contact pressure at the interface to vary while the patterned surface and the surface of the roller are in contact with each other; and

repositioning the stamp a plurality of times in a step and repeat manner to transfer the arrangement of pattern elements to a plurality of different portions of the surface of the roller and form an array of pattern elements, wherein a stitching error between adjacent pattern elements in the array is less than about 10 μm.

12. The method of claim 11, wherein the stitching error between adjacent pattern elements in the array is less than about 1 μ ι η.

13. The method of claim 11, wherein the stamp is a parallelepiped comprising a parallelogram cross-section and the pattern elements in the array comprise parallelogram tiles.

14. The method of claim 13, wherein the tiles are arranged helically on the surface of the roller.

15. A method of applying a pattern to a non-planar outer surface of a cylindrical roller, the method comprising imparting an arrangement of parallelogram pattern elements to the outer surface to form a helical array of pattern elements, wherein each pattern element comprises a transverse dimension greater than 0 and less than about 5 microns.

Background

Cylindrical tool rolls are used in a variety of industrial operations, particularly roll-to-roll manufacturing. Microstructured cylindrical tool rolls comprising structured patterns with length dimensions on the order of a single micron and above can be manufactured using a diamond turning machine that uses a diamond tipped tool to cut copper on a precision lathe. However, this method is fundamentally a turning operation, which limits the size and pattern geometry of structures that can be reproducibly cut into the surface of a non-planar substrate, such as a cylindrical tool roll.

Lithography and laser ablation may be used in order to fabricate nano-sized (greater than about 10nm and less than about 1 micron) features and patterns on non-planar surfaces, but these techniques produce oversized features, offer limited options for pattern geometry, or require unacceptably long patterning times.

Microcontact printing can be used to transfer two-dimensional nanoscale patterns of structures onto non-planar substrates at relatively low cost. Microcontact printing transfers a pattern of functionalizing molecules to a substrate, the functionalizing molecules comprising functional groups that are attached to the substrate surface or the coated substrate surface via chemical bonds to form a patterned self-assembled monolayer (SAM). A SAM refers to a monolayer of molecules attached to a surface by chemical bonds and adopting a preferred orientation with respect to the surface and even with respect to each other.

The basic method of microcontact printing of SAMs involves applying an ink containing functionalizing molecules to a relief-patterned elastomeric stamp (e.g., a poly (dimethylsiloxane) (PDMS) stamp), and then contacting the inked stamp to a substrate surface (typically a metal or metal oxide surface) to form a SAM in the areas of contact between the stamp and the substrate. The metal surface may then be further processed to remove metal not protected by the SAM, thereby forming a two-dimensional nanoscale pattern on the fabrication tool.

The functionalized molecule should be reproducibly transferred from the elastomeric stamp to the metal substrate surface with the desired high resolution patterned SAM with the least number of defects. Pattern defects such as line blurs and voids should be minimized to ensure accurate SAM pattern resolution and reproducibility.

Disclosure of Invention

In general, the present disclosure relates to a method for printing a pattern of microstructures or nanostructures on at least a portion of a tool having a non-planar surface, such as a cylindrical roll suitable for use in a roll-to-roll manufacturing process. The printed pattern acts as an etch mask for subsequent processing steps that transfer the printed pattern into the non-planar surface of the tool. The dimensions of the relief-patterned stamp used in the printing process can vary widely in size, and in some embodiments, the stamp is laid down on a non-planar print layer in a step-and-repeat process to produce a number of individual prints that can be stitched together in a desired pattern to cover selected areas of the tool surface.

In embodiments of the printing process of the present disclosure, the contact force between the printing surface of the relief-patterned stamp and the non-planar surface of the tool is controlled and allows for varying the contact pressure between the printing surface and the non-planar surface of the tool.

In one aspect, the present disclosure is directed to a method of applying a pattern onto a non-planar surface, wherein at least a portion of the non-planar surface has a radius of curvature. The method comprises the following steps: providing a stamp having a major surface with a relief pattern of pattern elements extending away from a base surface, wherein each pattern element has a stamping surface with a lateral dimension greater than 0 and less than about 5 microns, and wherein the stamping surface comprises an ink having functionalized molecules with functional groups chemically bonded to non-planar surfaces; positioning the stamp to cause rolling contact between the non-planar surface and a major surface of the stamp; contacting the stamping surface of the pattern element with the non-planar surface to form a self-assembled monolayer (SAM) of functionalized molecules on the non-planar surface and to impart an arrangement of the pattern element to the non-planar surface; and translating a major surface of the stamp relative to the non-planar surface, wherein translating the major surface of the stamp comprises: (1) controlling a contact force at an interface between the stamping surface and the non-planar surface, and (2) allowing a contact pressure at the interface to vary when the stamping surface and the non-planar surface are in contact with each other.

In another aspect, the present disclosure is directed to an apparatus for applying a pattern to a non-planar surface having at least one portion with a radius of curvature. The apparatus comprises: a stamp having an elastomeric stamp with a first major surface, wherein the first major surface of the stamp has a relief pattern of pattern elements extending away from a base surface, and wherein each pattern element has a stamping surface with a lateral dimension greater than 0 and less than about 5 microns, an ink imbibed into the stamping surface, the ink including a functionalizing molecule having a functional group chemically bonded to the non-planar surface; a first motion controller supporting the stamp and adapted to move the stamp relative to the non-planar surface; a second motion controller adapted to move the non-planar surface; and a force controller for controlling a force at an interface between the stamping surface and the non-planar surface on the stamp; wherein the first motion controller and the second motion controller move the stamp and the non-planar surface in a relative motion such that the stamping surface contacts the non-planar surface to impart the arrangement of pattern elements to the non-planar surface, and wherein the relative motion between the stamp and the non-planar surface is adjusted by the force controller to: (1) controlling a contact force at an interface between the stamping surface and the non-planar surface, and (2) allowing a contact pressure at the interface to vary when the stamping surface and the non-planar surface are in contact with each other.

In another aspect, the present disclosure is directed to a method of applying a pattern to an outer surface of a roller. The method includes imbibing an ink into a major surface of the stamp, the ink including a functionalizing molecule having a functional group selected for chemical bonding to the outer surface of the roller, wherein the major surface of the stamp has a relief pattern of pattern elements extending away from a base surface, and wherein each pattern element has a stamping surface with a lateral dimension greater than 0 and less than about 5 microns; contacting the stamping surface of the pattern element with the surface of the roller to bond the functional groups to the surface of the roller to form a self-assembled monolayer (SAM) of functionalized molecules on the surface of the roller and to impart an arrangement of the pattern element to the surface of the roller; translating a major surface of the stamp relative to a surface of the roller, wherein translating the major surface of the stamp comprises: (1) controlling a contact force at an interface between the patterned surface and the surface of the roller, and (2) allowing a contact pressure at the interface to vary when the patterned surface and the surface of the roller contact each other; and repositioning the stamp a plurality of times in a step-and-repeat manner to transfer the arrangement of pattern elements to a plurality of different portions of the surface of the roll and form an array of pattern elements, wherein a stitching error between adjacent pattern elements in the array is less than about 10 μm.

In another aspect, the present disclosure is directed to a method of applying a pattern to a non-planar outer surface of a cylindrical roller, the method comprising imparting an arrangement of parallelogram pattern elements to the outer surface to form a helical array of pattern elements, wherein each pattern element has a transverse dimension greater than 0 and less than about 5 microns.

The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.

Drawings

Fig. 1A-1B are schematic side views of a microcontact printing process in which a cylindrical roller having a non-planar metal surface is in rolling contact with an elastomeric stamp impregnated with a SAM-forming molecular species, and the SAM-forming molecular species is transferred from the stamping surface of the stamp to the non-planar metal surface to form a nanoscale pattern thereon.

Fig. 2A is a schematic perspective view of an apparatus for micro-contact printing (MCP) on a non-planar substrate according to the present disclosure.

Fig. 2B is a schematic side view of an impression module of the MCP device of fig. 2A.

Fig. 2C is a schematic perspective view of an embodiment of a cylindrical roller that has been patterned using the MCP device of the present disclosure.

Fig. 2D is a schematic perspective view of a parallelepiped die having a parallelogram cross section.

FIG. 2E is a schematic top view of a helical stamp pattern made on a non-planar substrate using the stamp of FIG. 2D.

FIG. 3 is a schematic cross-sectional view of an embodiment of a stamp suitable for microcontact printing.

Fig. 4A-4B are schematic cross-sectional views of a process for forming a self-assembled monolayer (SAM) on a substrate using a high aspect ratio stamp in a microcontact printing process.

Fig. 4C to 4D are schematic cross-sectional views of a process of using the SAM manufacturing tool of fig. 4A to 4B.

Fig. 5 is a top view of a tiled 3 x 3 impression pattern of the SAM of example 1 applied on a non-planar surface of a cylindrical roll.

Fig. 6 is a photograph of the etched pattern of the SAM from example 1 taken with an optical microscope.

FIG. 7 is a photograph taken with a scanning electron microscope of some of the etched lines from the pattern of FIG. 7.

Fig. 8 is a photograph taken using a scanning electron microscope of a line formed by reactive ion etching using the SAM of example 2 as a mask.

In the drawings, like numbering represents like elements.

Detailed Description

Referring to fig. 1A, a cylindrical roll 10 has a non-planar surface 12 that is located on a thin metal layer 14. The stamping surface 16 of the stamp 18 contains a SAM-forming molecular species (not shown in fig. 1A) that is to be applied to the non-planar surface 12 to form a corresponding pattern thereon. In FIG. 1A, the non-planar metal surface 12 will be patterned by rolling contact with the stamping surface 16 of the stamp 18. To achieve rolling contact, the roller 10 is rotated in the direction "R" while the stamp 18 is translated along the track in the direction "D" to initiate printing contact between the stamping surface 16 and the non-planar metal surface 12 at the initial contact point 20. The rotational speed in direction "R" is such that the tangential surface speed of the metallic non-planar surface 12 is substantially equal to (± 5%) the speed of movement in direction "D" to minimize or eliminate slippage at the initial contact point 20. The stamping surface 16 and the non-planar metal surface 12 remain in substantially steady-state contact such that at any given time, only a portion of each surface is in contact with only a portion of the other surface, but the portion of each surface in contact with that portion of the other surface is constantly changing.

Referring to fig. 1B, cylindrical roller 10 is rolled over stamping surface 16 to maintain a substantially constant force between stamping surface 16 and non-planar metal surface 12, and a pattern of SAM-forming molecular species 22 is applied to non-planar metal surface 12. When the stamp 18, which in some embodiments is made of an elastomeric material, is in rolling contact with respect to the non-planar metal surface 12 to form the pattern 22, the contact area between the stamping surface 16 and the non-planar metal surface 12 continuously changes, resulting in a change in contact pressure. For example, the stamp 18 is compressed at the initial contact point 20, and the contact interface 24 between the stamp 18 and the non-planar metal surface 12 gradually increases as the rolling progresses to some near steady contact area. As the contact interface 24 approaches the final contact point 26 of the stamp 18, the contact area is reduced to a very small narrow line.

The present disclosure relates to an apparatus and method for controlling the onset, engagement, and disengagement of a stamp 18 from a non-planar surface 12 during a micro-contact printing process to reproducibly form nano-sized features 22 in a high resolution pattern on the non-planar surface 12. In various embodiments, the apparatus and methods of the present disclosure include controlling the contact force between the stamp 18 and the cylindrical roller 10.

In one embodiment, for example, after determining the location of the initial contact point 20 between the stamping surface 16 and the non-planar metal surface 12, the stamp 18 and the cylindrical roller 10 are translated relative to each other such that: (1) controlling the contact force between the stamp 18 and the roller 10 at the interface 24 between the stamping surface 16 and the non-planar surface 12, and (2) allowing the contact pressure at the interface 24 to vary when the stamping surface 16 and the non-planar surface 12 are in contact with each other.

Referring to fig. 2A, micro-contact printing apparatus 100 includes a rigid roll support 102 on which is mounted an air bearing mandrel 104. The roller 110, mounted for rotation on the axis of rotation 113 of the air bearing mandrel 104, comprises a non-planar surface 112 on a metal support roller 114.

The micro-contact printing apparatus 100 further includes a stamp module 150 mounted on a stage apparatus 152. The stamp module 150 may be moved in any direction along the x-axis and the z-axis with respect to the roller 110 using a stage apparatus 152. The apparatus 100 also includes a confocal distance sensor 154 that can be used to monitor the surface topography of a stamp mounted on the stamp module 150 (not shown in FIG. 2A). Metrology data of a stamp mounted on the surface 160 of the imprint module 150 can then be used to correct tilt (tip-tilt) misalignment and to confirm the exact lateral dimensions of the stamp to set the index position relative to the non-planar surface 112. The laser triangulation sensor 156 can be used, for example, to map run-out errors of the non-planar surface 112, which can be entered into a compensation table to set the pre-contact position of a stamp mounted on the surface 160.

Referring to fig. 2B, cylindrical roller 110 has a metallic non-planar surface 112 on a support roller 114 that rotates about axis R. The non-planar surface 112 may be patterned by rolling contact between the non-planar surface 112 and a stamping surface of an elastomeric stamp (not shown in FIG. 2B) mounted on a support station 155 of the stamping module 150. In some embodiments, the support station 155 is a vacuum chuck configured to hold a selected elastomeric stamp. The compliant elastomeric stamp may optionally be bonded to a rigid or semi-rigid support substrate to provide dimensional stability (e.g., glass, metal, or ceramic shims) prior to mounting the stamp on a test stand.

To achieve rolling contact, the roller 110 is rotated in direction R while the stamp mounted on the imprint module 150 is translated in the x-direction in FIG. 2B. The rotation speed of the roller 110 in the direction R is such that the tangential surface speed of the metallic non-planar surface 112 is equal to the movement speed of the imprint module in the x-direction, so that there is no slip at the point of contact between the imprint surface of the stamp and the non-planar surface 112.

The stamp module 150 includes a stage 162 that may be configured to tilt, or rotate an elastomeric stamp attached to the surface 160. The table 162 is mounted on a platform 163 that is slidably mounted in the housing 164 using air bearings and moves along an axis 184. The platform 163 is attached to at least one pneumatic balancing device 165. The position of the lands 163 is controlled by a voice coil actuator 166, which is also used to exert force control between the stamping surface of the stamp and the non-planar surface 112 of the roller 110. Closed loop force control at the interface between the stamping surface and the non-planar surface 112 of the stamp is achieved by providing feedback through a set of two force sensors 168, 170. The positive (upward) force in the y-direction is balanced between the force sensors 168, 170. The force control loop is fully balanced with the force sensor 170 when the stamp mounted on the surface 160 is not in contact with the non-planar surface 112.

Thus, a variety of techniques can be used to set the pre-contact stamp locations. For example, in the embodiment of fig. 2B (which is not intended to be limiting), the pre-stamp position may be set using position feedback from a capacitive distance sensor 176 using a coarse manual height adjustment screw 172 and a fine adjustment piezoelectric actuator 174. Once contact is established between the stamp and the non-planar surface 112, the force control loop is fully balanced with the force sensor 168. The transition between the force sensors 168, 170 occurs during contact initiation/separation, and in some preferred embodiments, the stamp module 150 may be calibrated to ensure that the transition between the force sensors occurs smoothly without bouncing, particularly because the stamp contacting the non-planar surface is elastic.

The carriage 165 is mounted on a linear motion stage 180 of the movable stage 152. The drive controls the roller spindle motion (C-axis in fig. 2A) and moves the rotational axis 113 to coordinate with the tangential linear motion along the x-direction of the linear motion stage 180. During microcontact printing, these motions are coordinated to cause rolling contact between the non-planar surface 112 and the stamping surface of a stamp mounted on the surface 160.

In some embodiments, the rotational speed of the roller 110 in the direction R and the resulting tangential surface speed of the metallic non-planar surface 112 are substantially equal to the speed of movement of the stamping surface of the stamp mounted on the surface 160 along the x-direction such that there is substantially no slippage or deformation at the point of contact between the non-planar metallic surface 112 and the stamping surface.

In some embodiments, prior to contacting the stamping surface of the stamp with the non-planar surface 112, the stage 180 moves the stamp module 150 to place the mounted stamp on a track that results in a path to a predetermined initial contact point between a pattern element on a major surface of the stamp and the non-planar surface 112. The initial point of print contact between the stamp and the non-planar surface may be determined by a detector or combination of detectors, for example, a manual height adjustment screw 172 for coarse adjustment and a piezoelectric actuator 174 for fine adjustment. Stage 162 may also be adjusted to adjust the relative positions of the stamping surface and the non-planar surface, and to determine an initial point of contact or to trace the stamping surface to contact the non-planar surface at a predetermined point or area.

In a microcontact printing method, after initiating rolling contact between a stamping surface and a non-planar surface, the stamping surface is contacted with the non-planar surface for a printing time sufficient to chemically bond functional groups to the non-planar surface to form a self-assembled monolayer (SAM) of functionalized material on the non-planar surface and impart an arrangement of nanoscale pattern elements to the non-planar surface. The stamping surface of the stamp is translated relative to the non-planar surface of the roller such that: (1) controlling a contact force at an interface between the stamping surface and the non-planar surface, and (2) allowing a contact pressure (force per unit area) at the interface between the stamping surface and the non-planar surface to vary when the stamping surface and the non-planar surface are in contact with each other. For example, in some embodiments, a substantially fixed value (± 5%) of the contact force is maintained at the interface between the stamping surface and the non-planar surface.

In some embodiments, for example, with sensors 168, 170, the contact force at the interface between the stamping surface and the non-planar surface is maintained via closed loop force control that controls the pneumatic balancing device 165 and the voice coil actuator 166. The force control loop is fully balanced with the force sensor 170 when the stamping surface is not in contact with the non-planar surface of the roller, and with the force sensor 168 once contact between the stamping surface and the non-planar surface roller has begun.

In some embodiments, after translating the stamp, the stamping surface disengages from the non-planar surface and optionally returns to the starting position.

In various embodiments, the resulting interference between the non-planar surface and the unloaded stamping surface at the point of contact is less than about 25 microns, or less than about 5 microns, or even less than about 1 micron.

Referring again to fig. 2A-2B, in some embodiments, the linear motion stage 180 is itself mounted on a second linear motion stage 182 oriented to translate the linear motion stage 180 and the rest of the device 150 it supports along the z-direction and perpendicular to the x-and y-directions. This allows additional instances of the pattern on the stamping surface to be applied not only circumferentially in a step-and-repeat manner to the non-planar surface 112, but also in a direction parallel to the axis of the cylindrical roller 110. The distance sensor 156 may be used to measure the distance from itself to the non-planar surface 112, which in turn may be used to plot the runout on the cylindrical roll 110.

For a step and repeat process, in one embodiment, the stamp and tool diameters are sized so that an integer number of printed stamp tiles will precisely wrap around the circumference of the tool. The stamp is laid down on the roller in a grid pattern and forms a patterned area that is continuous around the circumference of the roller. This embodiment is illustrated in fig. 2C, which is a perspective view of an isolated cylindrical roll 110, wherein nine instances of the pattern 167 are laid out on the non-planar surface 112 in a three-by-three array of step and repeat fashion. Nine instances in the depicted embodiment are equally spaced apart in either the circumferential or axial direction or both, which is referred to herein as a splice error. However, it is contemplated in the present disclosure that instances of the pattern 167 may be immediately adjacent or even intentionally overlapping. The gap between adjacent instances of the pattern 167 on the non-planar surface 112 can be adjusted with a high degree of accuracy, even less than 2 μm.

Fiducial markers 169, each of which has a particular positional relationship of one of the patterns 167, may also be seen in FIG. 2C. It is contemplated that the fiducial marks 169 may be applied from the same stamp and at the same time as the pattern is applied. The fiducial marks 169 may also be applied in a separate operation. Such fiducial marks 169 are known in the art and in some cases may be convenient when using cylindrical roll 110 after patterning in, for example, a roll-to-roll operation on a web, and it is desirable to accurately register some secondary operations with the results of cylindrical roll 110 on the web.

In another embodiment shown in fig. 2D, the stamp 118 is made as a parallelogram prism (parallelepiped) with a length l, a width w and an angle θ selected to provide a cross-section 119 having a parallelogram shape. Referring to FIG. 2E, the parallelepiped stamp 118 of FIG. 2D may be used to transfer a pattern 140 to a non-planar circumferential tool surface 132 having parallelogram tile-shaped pattern elements 139. As schematically shown in fig. 2E, to form tiling pattern 140, each successive parallelogram-shaped tile 139 (numbered 1-9 in the order of application) is successively applied to surface 132 and shifted circumferentially in the circumferential direction CD and axially in the axial direction AD on surface 132 of non-planar surface 132 simultaneously such that the tiles are printed on surface 132 in a spiral configuration. In this arrangement, the circumference of the roller does not have to be an integer multiple of the stamp length l (fig. 2D). While this relaxes the absolute dimensional tolerance of the stamp length, there is an additional limit to the parallelogram angle that can be controlled to ensure that the pattern area is continuous around the circumference of the roller. For example, if the width w of the stamp 118 of fig. 2D is known and the perimeter TC of the non-planar surface 132 of the tool is known, the angle θ of the stamp can be determined by tan θ TC/w.

In various embodiments, the presently described microcontact printing process can impart an array of nanoscale pattern elements to a non-planar surface of a roller, wherein the lateral dimension of each nanoscale pattern element is less than about 5 microns. The array comprises a plurality of tile-like elements arranged such that adjacent tile-like elements are spaced apart by less than about 10 μm, less than 5 μm, less than 1 μm, or less than 0.1 μm, or even less than 0.02 μm, or overlap by a predetermined amount of less than about 10 μm, less than 5 μm, less than 1 μm, or less than 0.1 μm, or even less than 0.02 μm. These small patterns can be applied over the non-planar surface of a cylindrical roll having a height of about 9 inches (23cm) and a base of 12.75 inches (32.39cm) in diameter, which can be used in a roll-to-roll manufacturing process.

Fig. 3 shows a schematic view of a portion of a micro-contact printing stamp 210 comprising a substantially planar base surface 212. The array of pattern elements 214 extends away from the base surface 212. In some embodiments, the stamp 210 is a single piece of elastomeric material, and in other embodiments, may include elastomeric pattern elements 214 supported by an optional reinforcing backing layer 211. The array of pattern elements 214 on the base surface 212 of the stamp 210 may vary widely depending on the intended microcontact printing application, and may include, for example, regular or irregular patterns of elements, such as lines, dots, polygons, and combinations thereof.

The pattern elements 214 in the array on the base surface 212 may be described in terms of their shape, orientation, and size. The pattern element 214 has a base width x at the base surface 212 and includes a stamping surface 216. The stamping surface 216 resides at a height h above the base surface 212 and has a lateral dimension w, which may be the same as or different from the base width x. In various embodiments, the aspect ratio of the height h of the pattern elements 214 to the width w of the stamping surface 216 of the pattern elements 214 is about 0.1 to about 5.0, about 0.2 to about 3.0, or about 0.2 to about 1.0.

The methods and apparatus described herein are particularly advantageous for small pattern elements 214 having a stamping surface 216 with a minimum lateral dimension w of less than about 10 μm, or less than about 5 μm, or less than about 1 μm. In the embodiment shown in fig. 3, the stamping surface 216 is substantially planar and substantially parallel to the base surface 212, although such a parallel arrangement is not required. The methods and apparatus reported herein are also particularly advantageous for microcontact printing using pattern elements 214 having a height h of about 50 μm or less, or about 10 μm or less, or about 5 μm or less, or about 1 μm or less, or about 0.25 μm or less.

The pattern elements 214 may occupy all or only a portion of the base surface 212 (some areas of the base surface 12 may be free of pattern elements). For example, in various embodiments, the spacing l between adjacent pattern elements may be greater than about 50 μm, or greater than about 100 μm, or greater than about 200 μm, or greater than about 300 μm, or greater than about 400 μm, or even greater than about 500 μm. An array of commercially useful pattern elements 14 for microcontact printing covers, for example, about 0.1cm on the base surface 212 of the stamp 210²To about 1000cm²Or about 0.1cm²To about 100cm²Or about 5cm²To about 10cm²The area of (a).

In some embodiments, pattern elements 214 may form a "micropattern," which in the present application refers to an arrangement of dots, lines, filled shapes, or a combination thereof having a dimension (e.g., line width) of about 1 μm to about 1 mm. In some embodiments, the arrangement of dots, lines, fill shapes, or combinations thereof has a dimension (e.g., line width) of at least 0.5 μm, and typically no greater than 20 μm. The size of the micropattern pattern elements 214 may vary depending on micropattern selection, and in some embodiments, the micropattern elements have a size (e.g., line width) of less than 10 μ ι η, 9 μ ι η, 8 μ ι η, 7 μ ι η,6 μ ι η, or 5 μ ι η (e.g., 0.5 μ ι η to 5 μ ι η, or 0.75 μ ι η to 4 μ ι η).

In some embodiments, pattern elements 214 may form a "nanopattern," which refers to an arrangement of dots, lines, filled shapes, or combinations thereof having a dimension (e.g., line width) of about 10nm to about 1 μm. In some embodiments, the arrangement of dots, lines, fill shapes, or combinations thereof has a dimension (e.g., line width) of about 100nm to about 1 μm. The dimensions of the nanopattern elements 214 may vary depending on the nanopattern selection, and in some embodiments, the nanopattern elements have dimensions (e.g., line widths) of less than 750nm, less than 500nm, less than 250nm, or less than 150 nm.

In some embodiments, a combination of micropattern elements and nanopattern elements may be used.

In some embodiments, the pattern elements are traces, which may be straight or curved. In some embodiments, the pattern elements are traces that form a two-dimensional network (i.e., a grid). The grid includes traces defining open cells. The mesh may be, for example, a square grid, a hexagonal mesh, or a pseudo-random mesh. Pseudo-random refers to trace arrangements that lack translational symmetry but can be obtained from a deterministic manufacturing process (e.g., lithography or printing) that includes, for example, a computational design process that includes generating pattern geometries with a stochastic algorithm. In some embodiments, the grid has an open area fraction (i.e., a pattern element density of between 0.25% and 20%) of between 90% and 99.75%. In some embodiments, the grid has an open area fraction (i.e., a pattern element density of between 0.5% and 5%) of between 95% and 99.5%. The pattern elements may have a combination of the above aspects, for example, they may be curved traces, form a pseudo-random grid, have a density of between 0.5% and 5%, and have a width of between 0.5 μm and 5 μm. In other embodiments, the pattern elements may have a pattern element density of greater than 20%, or greater than 60%, or greater than 80%, or even greater than 90%, and may appear as a dark background with a small open area fraction.

Referring to FIG. 4A, the ink 320 including the functionalizing molecules is absorbed into the stamp 310 and resides on the stamping surface 316 of the stamp 310. The functionalizing molecules in the ink 320 include functional groups selected for bonding to the selected surface material 322 on the non-planar surface. The non-planar surface is supported by a support layer 324, which in some embodiments may be part of a cylindrical roller (not shown in fig. 4).

Referring to fig. 4B, the stamp 310 is positioned and brought into contact with the tool substrate 335. Tool substrate 335 includes a print layer 322 having a non-planar surface 326, a tool layer 323, and a cylindrical roll substrate 324. In various embodiments, which are not intended to be limiting, the tool layer 323 is a hard, Reactive Ion Etchable (RIE) material such as a metal or metal alloy selected from, for example, aluminum, tungsten, and alloys and combinations thereof, a non-metallic inorganic such as glass, quartz, silicon, diamond-like glass (DLG), or diamond-like carbon (DLC). The cylindrical roll substrate 324 is a metal suitable for diamond turning operations, and non-limiting examples include copper, aluminum, and alloys and combinations thereof. As will be appreciated by those skilled in the art, the cylindrical roll substrate may be composed of a variety of materials that enable diamond turning of the surface while providing a more robust underlying structure, such as copper on steel. The material used for the print layer 322 will be discussed in more detail below. In addition, one or more optional adhesion promoter layers may be used to enhance the adhesion between the layers. The adhesion promoter layer is typically a few nanometers thick and is not shown in fig. 4.

The stamping surface 316 contacts the first portion 325 of the surface 326. The functionalized molecules in ink 320 are contacted with surface 326 for a printing time long enough to allow the functional groups to chemically bond to the surface (the contacting step is not shown in fig. 4B). In various embodiments, the printing time is from about 0.001 seconds to about 5 seconds, or from about 0.010 seconds to about 1 second.

The stamping surface 316 is then removed, and the ink remaining on the surface 326 forms a self-assembled monolayer (SAM)330 on the first portion 325 of the surface 326, depending on the shape and size of the stamping surface 316. A portion 327 of surface 326 contiguous with first portion 325 remains free of SAM 330.

Referring to fig. 4C, portions 327 of print layer 322 not underlying SAM330 are removed by any suitable process, such as wet chemical etching, to form a layer having a height h of less than about 500nm, or less than about 250nm, or less than about 100nm, or less than about 50nm₁The pattern element 352. The etching process further exposes regions 350 of the tool layer 323.

Referring to fig. 4D, the remaining portions of the tool substrate 335 may optionally be further processed by using an additional etch, such as a Reactive Ion Etch (RIE), to remove portions of the tool layer 323 not covered by the pattern elements 352. The RIE process produces high aspect ratio pattern features 360 having an aspect ratio of about 0.1 to about 10, or about 0.25 to about 7, and may optionally expose regions 370 of the cylindrical rollers in some embodiments.

In an optional further processing step not shown in fig. 4A-4D, the tool substrate 335 may be further processed to peel off the SAM330 and the print layer 322 in the high aspect ratio pattern elements 360, leaving a portion of the tool layer 323 on the cylindrical roll substrate 324.

The stamp 310 used in the MCP process of the present disclosure should be sufficiently elastic to allow the stamping surface 316 to very closely conform to the fine irregularities in the surface 326 of the print layer 322 and to completely transfer the ink 320 thereto. This elasticity enables stamp 310 to accurately transfer functionalized molecules in ink 320 to a non-planar surface. However, the pattern elements 314 should not be so elastic that when the stamping surface 316 is lightly pressed against the surface 326, the pattern elements 314 deform to cause blurring of the ink 320 on the substrate surface 326.

The stamp 310 should also be formed such that the stamping surface 316 includes an absorbing material selected to absorb the ink 320 to be transferred onto the surface 326 to form a SAM330 thereon. The stamping surface 316 can swell to absorb ink 320, which can include functionalized molecules alone or suspended in a carrier such as an organic solvent. In some cases, such swelling and absorption characteristics may provide good definition of the isolated SAM330 on the substrate surface 326, but should generally be minimized to improve dimensional control of the stamping surface 316. For example, if the dimensional features of stamping surface 316 have a particular shape, surface 316 should transfer ink 320 onto surface 326 of print layer 322 to form SAM30 that mirrors the features of stamping surface 316 without blurring or smearing. The ink is absorbed into the stamping surface 316, and when the stamping surface 316 contacts the material surface 326, the ink 320 is not dispersed, but the functional groups on the functionalizing molecules chemically bond to the surface 326, and removing the stamping surface 316 from the surface 326 results in a SAM330 with well-defined features.

Useful elastomers for forming stamp 310 include polymeric materials such as silicone, polyurethane, ethylene propylene diene M-type (EPDM) rubber, and commercially available flexographic printing plate materials (e.g., those commercially available under the trade designation Cyrel from dupont DE Nemours and Company, Wilmington, DE, wilford, inc.). The stamp may be made of a composite material including, for example, an elastomeric material combined with a woven or non-woven fiber reinforcement 311 (fig. 4A) on the stamping surface 316.

Polydimethylsiloxane (PDMS) is particularly useful as an impression material because it is elastomeric and has a low surface energy (which makes it easy to remove the impression from most substrates). Commercially available formulations that are useful are available from Dow Corning, Midland, Mich under the tradename Sylgard184 PDMS. PDMS stamps can be formed, for example, by dispensing an uncrosslinked PDMS polymer into or against a patterned mold, followed by curing. The master for molding the elastomeric stamp can be formed using lithographic techniques known in the art (e.g., photolithography, electron beam). An elastomeric stamp can be molded against a master by applying uncured PDMS to the master and then curing.

Print layer 322 and ink 320 are selected such that the functionalizing molecules therein include functional groups that bond to surface 326 of layer 322. The functional group may reside at the physical end of the functionalized moleculeThe termini, as well as any portion of the molecule that remains exposed when the molecule participates in SAM formation, may be used to form a chemical bond with surface 326 in such a manner that the molecular species may form SAM 330. In some embodiments, the functionalizing molecules in ink 320 may be viewed as having first and second terminals separated by a spacer portion, the first terminal comprising a functional group selected for bonding to surface 326, and the second terminal group optionally comprising a functional group selected for providing SAM330 on material surface 326 having a desired exposed functional group. The spacer portion of the molecule can be selected to provide a particular thickness of the resulting SAM330, as well as to facilitate SAM formation and control transport mechanisms (e.g., vapor transport). Although the thickness of the SAMs of the present invention may vary, they have a thickness of less than aboutSAMs having a thickness of less than about are generally preferred, and more preferably having a thickness of less than aboutAnd more preferably has a thickness of less than aboutSAM of thickness (g). These dimensions are generally determined by the choice of the molecular species 20 and particularly the spacer portion thereof.

In addition, the SAM330 formed on surface 326 may be modified after such formation for various purposes. For example, the functionalizing molecules in ink 320 may deposit on surface 326 in the SAM, the functionalizing molecules having exposed functional groups that include protecting groups that can be removed to effect further modification in SAM 330. Alternatively, reactive groups may be provided on exposed portions of the functionalizing molecules in ink 320, which may be activated or deactivated by electron beam lithography, x-ray lithography, or any other radiation. Such protection and deprotection can facilitate chemical or physical modification of existing surface bound SAM 330.

SAM330 is formed on surface 326 of print layer 322. The substrate surface 326 may be substantially planar and have a slight curvature, or may have a significant curvature similar to the surface of a cylindrical roll described above. Useful materials for print layer 322 can include inorganic materials (e.g., metal or metal oxide materials, including polycrystalline materials) coated on a metal or glass support layer. The inorganic material used for the print layer 322 may include, for example, elemental metals, metal alloys, intermetallic compounds, metal oxides, metal sulfides, metal carbides, metal nitrides, and combinations thereof. Exemplary metallic print layers 322 for supporting the SAM include gold, silver, palladium, platinum, rhodium, copper, nickel, iron, indium, tin, tantalum, aluminum, and mixtures, alloys, and compounds of these elements. Gold is the preferred metal surface 322.

The print layer 322 on the support substrate 324 may have any thickness, such as from about 10 nanometers (nm) to about 1000 nm. The inorganic material coating may be deposited by any convenient method, such as sputtering, evaporation, chemical vapor deposition or chemical solution deposition (including electroless plating), among others known in the art.

In one embodiment, the combination of the material used for print layer 322 and the functional group of the functionalizing molecule used in ink 320 includes, but is not limited to: (1) metals such as gold, silver, copper, cadmium, zinc, palladium, platinum, mercury, lead, iron, chromium, manganese, tungsten, and any of the above alloys having sulfur-containing functional groups such as thiols, sulfides, disulfides, and the like.

Additional suitable functional groups on the functionalizing molecules in ink 320 include acid chlorides, anhydrides, sulfonyl groups, phosphoryl groups, hydroxyl groups, and amino acid groups. Additional surface materials for print layer 322 include germanium, gallium, arsenic, and gallium arsenide. Additionally, epoxy compounds, polysulfone compounds, plastics, and other polymers may find use as the material for the print layer 322. Additional materials and functional groups suitable for use in the present invention can be found in U.S. patent nos. 5,079,600 and 5,512,131, which are incorporated herein by reference in their entirety.

Referring again to fig. 4A-4D, in some embodiments, the functionalizing molecules used to form the SAM in the presently described process are delivered to the stamp 310 as an ink solution 320 that includes one or more organosulfur compounds as described in U.S. published application No. 2010/0258968, which is incorporated herein by reference. Each organosulfur compound is preferably a thiol compound capable of forming a SAM330 on the selected surface 326 of the print layer 322. Thiols (thiols) include- -SH functional groups and may also be referred to as thiols (thiols). Thiol groups may be used to form chemical bonds between molecules of the functionalizing compound in the ink 320 and the surface 322 of the metal printed layer. Useful thiols include, but are not limited to, alkyl thiols and aryl thiols. Other useful organic sulfur compounds include dialkyl disulfides, dialkyl sulfides, alkyl xanthates, dithiophosphates, and dialkyl thiocarbamates.

Preferably, the ink solution 320 includes an alkyl thiol such as a linear alkyl thiol: HS (CH)₂)_nX, where n is the number of methylene units and X is the terminal group of an alkyl chain (e.g., X ═ CH₃、--OH、--COOH、--NH₂Etc.). Preferably, X ═ CH₃. Other useful functional groups include, for example, those described below: (1) ulman's "Formation and Structure of Self-Assembled Monolayers," Chemical Reviews, volume 96, pages 1533 and 1554 (1996); and (2) Love et al, "Self-Assembled Monolayers of microorganisms on Metals as a Form of nanotechnology," Chemical Reviews, p.105, p.1103-.

Useful alkyl thiols can be linear alkyl thiols (i.e., linear alkyl thiols) or branched alkyl thiols, and can be substituted or unsubstituted. The optional substituents preferably do not interfere with SAM formation. Examples of useful branched alkyl thiols include alkyl thiols having a methyl group attached to every three or every four carbon atoms of a linear alkyl backbone (e.g., phytanyl thiols). Examples of mid-chain substituents within useful alkyl thiols include ether groups and aromatic rings. Useful thiols can also include three-dimensional cyclic compounds (e.g., 1-adamantanethiol).

Preferred linear alkyl mercaptans have from 10 to 20 carbon atoms (more preferably from 12 to 20 carbon atoms; most preferably 16 carbon atoms, 18 carbon atoms or 20 carbon atoms).

Suitable alkyl mercaptans include commercially available alkyl mercaptans (Aldrich Chemical Company, Milwaukee, Wis.) from Milwaukee, Wis.). Preferably, the ink solution 320 consists essentially of a solvent and an organic sulfur compound, with the impurities comprising less than about 5 weight percent of the ink solution; more preferably less than about 1%; even more preferably less than about 0.1 wt%. Useful inks 320 can comprise a mixture of different organosulfur compounds, such as a mixture of an alkyl thiol and a dialkyl disulfide, dissolved in a common solvent.

Aryl thiols that include a thiol group attached to an aromatic ring may also be used in ink 320. Examples of useful aryl thiols include dithiol and trithiol. The dithiol and trithiol may be substituted with one or more functional groups at any of a number of positions. Other examples of useful aryl thiols include acenyl thiols that may or may not be substituted with functional groups.

Useful thiols can include straight chain conjugated carbon-carbon bonds, such as double or triple bonds, and can be partially or fully fluorinated.

The ink solution 320 may include two or more chemically distinct organosulfur compounds. For example, the ink may comprise two linear alkyl thiol compounds each having a different chain length. As another example, the ink 320 may include two linear alkyl thiol compounds with different tail groups.

Although microcontact printing has been performed by inking the stamp with pure organosulfur compounds, with linear alkyl thiols and PDMS stamps, delivery of organosulfur compounds to the stamp can be more uniformly achieved with less stamp swelling if delivered from solvent-based inks. In some embodiments, the ink includes more than one solvent, but the most useful formulations need only include a single solvent. Inks formulated with only one solvent may contain very small amounts of impurities or additives (e.g., stabilizers or drying agents).

Useful solvents are preferably compatible with the most commonly used impression materials PDMS for micro-contact printing (i.e., they do not excessively swell the PDMS). In microcontact printing, swelling of the PDMS stamp can lead to deformation of the patterned features and poor pattern fidelity. Depending on the method of inking, excessive swelling may also present more significant challenges in providing mechanical support to the stamp.

Ketones may be suitable solvents for the ink solution. In some embodiments, suitable solvents include, for example, acetone, ethanol, methanol, methyl ethyl ketone, ethyl acetate, and the like, and combinations thereof. In some embodiments, the solvents are acetone and ethanol. The one or more organosulfur compounds (e.g., thiol compounds) are present in the solvent at a total concentration of at least about 3 millimolar (mM). As used herein, "total concentration" refers to the molar concentration of all dissolved organosulfur compounds taken together. The one or more organosulfur compounds (e.g., thiol compounds) can be present in any total concentration wherein the ink solution consists essentially of a single phase. The one or more organosulfur compounds (e.g., thiol compounds) can be present in a total concentration of at least about 5mM, at least about 10mM, at least about 20mM, at least 50mM, and even at least about 100 mM.

The stamp 310 may be "inked" with an ink solution 320 as described herein using methods known in the art (e.g., as described in Libioulle et al, "Contact-ink Stamps for Microcontact Printing of Alkanethiols on Gold," Langmuir (Langmuir) Vol.15, p.300-304 (1999)). In one method, an applicator (e.g., a cotton swab or foam applicator) impregnated with the ink solution 320 may be used to wipe across the stamping surface 16 of the stamp 310, followed by drying the solvent on the stamping surface 316. In another approach, the stamping surface 316 may be pressed against an "ink pad" impregnated with an ink solution, the ink pad optionally being a PDMS slab. In another method, the stamp can be loaded with an ink solution from the back of the stamp relative to the printing surface. In the latter method, the organosulfur compound diffuses through the stamp to reach the relief-patterned side (the side including the planar surface 312 and the pattern element 314 having the stamping surface 316) for printing. In another embodiment, the relief-patterned printing side of the stamp can be immersed in an ink solution, then removed and dried ("ink-impregnated").

The apparatus of the present disclosure will now be further described in the following non-limiting examples.