WO2016071760A2

WO2016071760A2 - Laser patterning of cylinders for printing, imprinting, embossing, and inverse offset, for 3d patterning

Info

Publication number: WO2016071760A2
Application number: PCT/IB2015/002206
Authority: WO
Inventors: Torbjorn Sandstrom
Original assignee: Mycronic Mydata Ab
Priority date: 2014-11-03
Filing date: 2015-11-03
Publication date: 2016-05-12
Also published as: WO2016071760A3

Abstract

The present disclosure relates to a method for making high precision patterned cylinders with arbitrary patterns and without a seam. In particular it relates to a method forming a 3D nano printing surface with non-binary features on a cylindrical form forming a seamless 3D latent image in a resist layer on a cylinder, developing the 3D latent image and directionally etching away the developed resist and a portion of the exterior surface of the cylindrical to a 3D onto the surface of the cylindrical.

Description

LASER PATTERNING OF CYLINDERS FOR PRINTING, IMPRINTING, EMBOSSING, AND INVERSE OFFSET, FOR 3D PATTERNING

Inventors: Torbjorn Sandstrom

RELATED APPLICATION

[0001] This application claims the benefit of US Provisional Application No. 62/074,582, filed 3 November 2013 (Attorney docket no. MLSE 1147-1), and US Provisional Application No. 62/103,540 (Attorney docket no. MLSE 1147-2), which are incorporated by reference.

[0002] The technology disclosed relates to creating a pattern on a cylinder for use in roll to roll printing applications. There is a growing use of roll to roll printing, heat embossing, and nano-imprinting. For printed electronics pattern quality is critical, and at the same time the desired feature sizes are shrinking. In addition to printed electronics, printed and embossed surfaces are used for control of light, for example by Fresnel patterns, microlenses, microprisms, diffraction gratings, and light guiding structures. Printed and embossed surfaces may be patterned with binary patterns 102, as shown in Fig. 1A, 3D patterns 104, as shown in Fig. IB, or hybrid stepped patterns 106, as shown in Fig. 1C. As shown, binary patterns have only two types of area heights, 3D patterns may have continuous surfaces of varying height, and hybrid stepped patterns may include three or more discrete height areas.

[0003] Printing cylinders with the different pattern types described above may be manufactured by mechanical engraving or by laser machining, i.e. laser ablation of a pattern onto the cylinder. Mechanical engraving and laser machining have limitations in quality and flexibility. For precision patterns, for example for printed electronics or optical devices, a different method of may be used where a pattern for use with a printing cylinder is formed on a flat substrate, for example on a silicon wafer. Using the patterned flat substrate, a thin flexible copper or nickel shim replicating the pattern on the flat substrate can be made. The flexible shim, including the replicated pattern, is attached around the circumference a non-patterned cylinder. This method of replicating a pattern formed on a flat substrate allows the

manufacturing infrastructure of the semiconductor or flat panel display (FPD) industry to be used for creating patterns on cylinders. With this flexible shim method, both binary and 3D patterns can be made. The 3D pattern can be formed in photoresist which has high geometrical resolution and can form patterns with optical quality. The photoresist typically gives better surface finish than direct laser milling or ablation. However, the resist is too soft for use as a printing master, but the shims with the replicas are hard and durable and suitable for high volume production. An example use of the flexible shim method includes making a wire-grid polarizers with 50 nm lines by nanoimprintng from cylinders with an attached flat shim replicating an ebeam patterned 300 mm wafer.

[0004] A disadvantage of using a patterned flexible shim around a cylinder is that there will always be a seam in the pattern on the cylinder where the ends of the flexible shim meet. Due to the seam, the wiregrid polarizers in the example above cannot be larger than the wafer dimensions, for example the largest shim that can be made from a 300 mm wafer isl2 inches (300 mm) diagonal. Therefore, there is a need for a seamless cylinder allowing for the possibility to imprint arbitrarily large areas, for example patterned foils for an 80 inch TV screen or foils to be laminated to architectural glass. In addition to the seam issue, curving the flexible shim around a cylinder results in a loss in precision in the pattern. Therefore, there is a need for a method of producing a patterned cylinder without bending a pattern created on a flat surface around a cylinder.

[0005] The technology disclosed below addresses the seam and size noted problems above for printing cylinders.

SUMMARY

[0006] The present disclosure relates to a method for making high precision patterned cylinders with arbitrary patterns and without a seam. In particular it relates to a method forming a 3D nano printing surface with non-binary features on a cylindrical form forming a seamless 3D latent image in a resist layer on a cylinder, developing the 3D latent image and directionally etching away the developed resist and a portion of the exterior surface of the cylindrical to a 3D onto the surface of the cylindrical.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1 A illustrates a binary pattern.

[0008] FIG. IB illustrates a continuous 3D pattern.

[0009] FIG. 1C illustrates a hybrid stepped pattern.

[0010] FIG. 2A, 2B and 2C show an example embodiment of a spray coating process.

[0011] FIG. 3A, 3B and 3C illustrates plasma etching methods.

[0012] FIG. 4A, 4B, 4C, 4D and 4E illustrate process steps of exposing and developing a resist and etching a pattern into a substrate.

[0013] FIG. 5A, 5B and 5C illustrate a plasma processing device and method. DETAILED DESCRIPTION

[0014] The following detailed description is made with reference to the figures. Preferred embodiments are described to illustrate the technology disclosed, not to limit its scope, which is defined by the claims. Those of ordinary skill in the art will recognize a variety of equivalent variations on the description that follows.

[0015] The present disclose relates to a method of producing and using a seamless patterned cylinder with high precision. The seamless patterned cylinder may be produced by the following steps:

[0016] First a cylinder is provided, in embodiments the cylinder is solid, hollow or with internal trusses as appropriate. In embodiments, the outer surface is formed as a glossy cylinder by lathing or a similar process. The outer surface may be comprised of the bulk material of the cylinder or the outer surface maybe comprised of a deposited layer. For example the bulk material of deposited layer may be a metal like nickel or copper; a polymer; or an inorganic material like a ceramic, a glass-like material like glass, fused silica or diamond-like carbon, or hard carbon.

[0017] The prepared outer surface of the cylinder is coated with a resist. As used herein, the term resist may refer to any material that can be patterned and it does not necessarily imply any chemical sensitivity to light or energy beams, though materials with those properties may be used as the resist. The function of the resist is that a layer of the resist can aid in converting an energy beam to a surface pattern on the outer surface of the cylinder.

[0018] In embodiments, it is important that the coating of the resist onto the outer surface of the cylinder is uniform, free from defects and free from seams, as this will ensure high precision features and a seamless resulting pattern. In embodiments, methods of coating the outer surface of the cylinder with resist include coating by dipping, slit coating, meniscus coating, condensation from vapor, or by spraying the resist onto the outer surface of the cylinder. In embodiments, the resist coating may be dried, or hardened.

[0019] Figs. 2A-2C show an example embodiment of a spray coating process in which the cylinder 200 is held horizontally and the resist 202 is coated on the cylinder with overlapping passes with a spraying device 204 while the cylinder is rotated 208. In embodiments, several passes, and therefore coats of resist 202, may be used to cover the entire surface with an even and smooth layer of resist 206. In embodiments, for example embodiments including 3D patterns, it is desirable to apply several coats of resist to build up a thick layer of resist. As shown in Fig. 2C the rotation 208 of the cylinder keeps the resist from running as would occur in a non-rotating cylinder as shown in FIG. 2B. In embodiments, the spraying device 204 may be a spray gun similar to devices used for painting or the spraying device may be similar to an inkjet printing head. The atmosphere 210 around the cylinder during resist coating may be partially or fully saturated with a solvent, for example water, white spirit, or xylene. Partial of full saturation of the atmosphere with a solvent may be beneficially used in slowing the drying process of the resist film. For example, slowing the drying process is beneficial in order for spray drops from the spraying device to not dry before they have spread into an even coat on the surface. Further, surface tension properties of the resist may also aid in the smoothing of the surface in the short range as the resist dries. Long range thickness variations may be avoided with a uniform spraying pattern which deposits the same amount of resist everywhere on the surface. Further, the rotation of the cylinder makes gravitation forces on the resist average out to zero which also aids in smoothing the resist. The rotation 208 of the cylinder allows a thicker layer 212 to be applied than would be possible on a stationary cylinder 214 in addition to making the deposition of the resist even.

[0020] In embodiments the deposition rate is balanced with the drying rate in order to build up a thick layer of resist 212 without "orange-peel surface" or the striations inside the resist layer which may be a result from applying multiple coats of resist. The resist is applied continuously 216 and dries slowly, so that it is gradually dries without creating a skin on the surface. The drying may be done at essentially the same time as new resist is deposited and the balance between the deposition and drying is controlled by the deposition rate, the rotation rate, the agitation 218 of the atmosphere around the cylinder and the solvent saturation of the atmosphere 210. A controlled amount of solvent in the atmosphere not only slows down the rate of drying, but also keeps the resist from drying fully at the surface, thereby avoiding skin formation, "orange-peel surface" and makes newly sprayed resist wetter and more flowable on the surface it is deposited. For 3D patterns, for example for lenses and prisms, the resist layer may be built up to at least 10μιη-30 μιη or more.

[0021] Another embodiment of resist coating includes a dip coating process. In embodiments including dip coating, the resist is applied to the outer surface of the cylinder by vertically lowering the cycling into a reservoir of liquid resist. The cylinder is withdrawn slowly so a thin film of resist remains on the cylinder. The thickness of the deposited layer depends on the viscosity of the liquid resist, the withdrawal speed, the speed of solvent evaporation (which maybe be controlled in the atmosphere) and the temperature of the cylinder. Alternatively other conventional methods of coating a surface with a resist may be used for coating the outer surface of the cylinder. [0022] Following the coating of the outer surface with resist, the cylinder may be patterned by an energy beam appropriate for the resist, for example by visible or UV exposure of the resist. The patterning may include using single or multiple scanning beams, imaging of a spatial light modulator or mask, or by forming on optical transform of a spatial light modulator or mask. In embodiments, electron, ion, proton, neutral atom or an IR photon beam may be used. The exposure of the resist may take place by cross-linking, cutting or changing the conformation of resist molecules, by a reaction between different molecules species, by a phase change, by hardening or softening, by selective deposition, by a change in surface energy, or by evaporation or disintegration of material. The energy beam may be controlled by a data path which generates a pattern which seamlessly covers the entire circumference of a cylinder. The pattern may have fields or the pattern may be contiguous so that endless patterns can be created by rolling the cylinder multiple turns against a continuous foil.

[0023] One method for patterning the resist is laser ablation. In embodiments, the resist is a thin resist layer and a binary resist pattern is produced. In embodiments, the resist is a thick resist layer and laser ablation is used to create a 3D structure in the resist. The laser may be a picosecond or femtosecond laser and the resist material may be chosen so that good depth control is achieved. The laser pulses may be modulated with a mask or dynamically with a spatial light modulator (SLM) and wavelengths between vacuum UV and far infrared may be used, for example wavelengths between 193 and 1 100 nanometers will be found suitable, however use of wavelengths outside of this range an envisioned.

[0024] Another method to produce a pattern in a resist is to use a photon or electron sensitive resist layer. In this method, a latent image is formed in the resist by optical or electron exposure by a patterning beam and the resist is developed to produce the desired pattern or surface. Several different methods for optical patterning may be used, including; laser scanning, imaging a one-dimensional or a two-dimensional SLM or exposure by interferometry or holography, or through a mask. Wavelengths of electromagnetic radiation from extreme UV to far infrared may be used, most suitably between 193 and 600 nanometers, even more suitably between 350 and 450 nanometers where many photoresists are sensitive.

[0025] The patterning of the resist is controlled by a datapath supplying modulation data to the patterning beam based on the desired pattern and the position of the workpiece, here the cylinder. The cylinder has an actual circumference which may differ slightly from the nominal design value. In order to get a seamless pattern the pattern on the cylinder may be scaled so that an integer number of repeating features, e.g. lines, match the exact circumference of the cylinder. This scaling can be done in data or for small scaling errors it may be done in the control of the rotation of the cylinder while writing. Each feature is then written with the design scale, but the distance between features is slightly stretched, or compressed, to make the pattern seamless, i.e. without any local larger jump in the position of the features. Larger scaling errors or non-uniform errors may be corrected in the data.

[0026] Following the patterning exposure, the resist may be developed. In embodiments, the exposure creates a latent image which can be converted to a physical pattern by the development process. The development may be done using a chemically active fluid or gas or using a plasma, depending on the resist. In one example process, the chemical reactivity of the resist may be changed by the exposure and a silicon-containing chemical agent is selectively bound to exposed areas of the surface. In a subsequent plasma etching step the silicon acts as an etch mask, allowing the plasma to consume unexposed resist areas. Some processes do not require a development step since the physical pattern is formed during the exposure step, for example with laser ablation.

[0027] In embodiments, the resist may be wet developed. The cylinder may be held in a horizontal or tilted position and sprayed with developer while rotating. In embodiments the cylinder is tilted at a position of 20 to 60 degrees from horizontal which is advantageous since the flow of resist under gravity on the right and left side of the cylinder will form an angle to each other and thereby is less likely to produce artifacts in the pattern. At smaller angles than 20 degrees the advantageous effect is weaker since the flows are more parallel, at larger angles than 60 it is difficult to cover the entire area of the roll with developer. The most suitable angle range where there is a large enough angle between the flow directions and covering the entire surface is between 30 and 45 degrees from horizontal.

[0028] In embodiments including binary patterns, the resist is developed through the resist, i.e. until they expose the underlying layer. In embodiments including 3D patterns, the resist may not be patterned through to the underlying material of the outer surface of the cylinder, i.e. the depth of the profile is typically only part of the resist thickness, so no area of the underlying material is exposed. Hybrid stepped patterns may include the deepest step being developed through and other steps are developed only part of the way to the underlying material. Processes using plasma or gas development may be used as well for developing the latent resist image.

[0029] After a binary or 3D pattern is formed in the resist film, as discussed above, the pattern may be transferred to the underlying material of the outer surface of the cylinder by an etching process, such as plasma etching. As noted above, the outer surface of the cylinder is composed of a material that is more durable than the resist and therefore can be use many times. Conventional methods of plasma etching may be used in the transfer process. Plasma etching is a broad class of gaseous processes where the etching is induced by a gas discharge or by passing an electric current through the gas. Example processes include reactive ion etching (RIE) and physical sputter etching. For example, RIE may be used to transfer a pattern in resist into an underlying material. The RIE gradually consumes first the resist and then portions of the underlying material. Where the developed resist is thin the process etches deeper into the underlying material of the outer surface of the cylinder, thereby creating a replica of the resist pattern in the underlying material. Depending on the etch rates in resist and underlying materials the resist pattern may be scaled for a correct profile depth in the final pattern in the underlying material.

[0030] For binary patterns and where linewidth is relatively large, wet or gas-phase etching may be used. When there is no resist remaining on the surface, either prior to or during the etching process, the etchant reaches the cylinder and works its way into the underlying material, creating a depth pattern. Another method of etching through a binary mask is electrochemical etching, for example dissolving the material into an electrolyte when a current is passed through the openings in the resist.

[0031] For patterns with small features like holograms and for 3D patterns transfer by plasma etching may also be used. FIG. 3 illustrates a number of conventional plasma etching methods. In RIE, FIG. 3 A, ions 301 are generated by a plasma and accelerated towards the workpiece 303. In electron cyclotron resonance (ECR), FIG. 3B, and inductively couple plasma (ICP), FIG. 3C, the plasma is generated remotely by microwaves or inductively and ions 301 are extracted and made to impinge on the workpiece 303. In particular RIE and ICP give etch profiles with vertical walls. For binary patterns the plasma etching eats more or less

perpendicularly into the cylinder, making vertical walls and high aspect ratios possible, as well as features much narrower than the thickness of the resist or the height of the etched feature.

[0032] Furthermore, the etching properties depend on the type of reaction with the gases used and the process conditions. Plasma and ion etching can be tuned to eat both resist and underlying material with comparable rates. As shown in FIGs. 4A-E the thickness profile of the resist gets converted during the transfer process to a depth profile in the underlying material after all resist is consumed. Specifically, the embodiment of transfer illustrated in FIGs. 4A-E includes, providing a photomask 402 including a plurality of occupancies representing different depths of the pattern, exposing a photoresist 404 deposited on a substrate 406 through the photomask 402 with UV, developing the photoresist 404 resulting in a patterned thickness profile in the photoresist, and etching the photoresist 404 and substrate 406 which results in removal of all the photoresist and a patterned thickness profile in the substrate. Many types of plasma etching, in particular high performance RIE, RIBE, IBE, and physical sputtering are one- dimensional processes, i.e. they have a direction of action. Since a cylinder has area elements pointing in different directions and the ion beam hits it from many directions during rotation, it is difficult to get steep sidewalls.

[0033] In the technology disclosed, the etching is done by "perpendicular etching" as described below. Plasma processing of the cylinder 502 is done in a process chamber 504, as shown FIG. 5A, where the cylinder is rotated, and in embodiments also reciprocated along axis of the cylinder, all parts of the cylinder are given identical etching in order to create uniform height profile ranges throughout the outer surface of the cylinder. Furthermore the ion beam 506 is masked so that only a sector of the cylinder outer surface, essentially perpendicular to the trajectory of the ions, is exposed to the etching action, as is shown is FIGs. 5B and 5C. In embodiments, the etching takes place in small zone on one side of the cylinder and the zone may or may not cover the entire length of the cylinder. A plasma or ion beam generator 508 produces a directional beam and part of this beam may be used to etch the resist and the underlying durable material of the outer cylinder surface. The lateral extent of the beam is restricted by a mechanical beam mask 510 limiting the etching to a sector where the ions impinge essentially perpendicularly on the cylinder. In embodiments, the range of angles is chosen to be small enough to approximate perpendicular incidence of the ions. The beam is masked by a mechanical beam mask 510 exposing the cylinder within this angle range. With the same range of impingement angles a larger diameter cylinder can use a larger mask, FIG. 5C, than a small cylinder FIG. 5B, thereby etching more area per unit time.

[0034] The allowed angular range approximating perpendicular incidence may in an example embodiment be up to +/- 15 degrees, resulting in a 30 degree arc surface sector of the outer surface of the cylinder, for nearly vertical etched side walls. Since the cylinder rotates relative to the plasma etching hardware each point on the cylinder is etched by ions impinging from all angles within the allowed range of the mask in place. For +/- 15 degrees range the average impingement angle for an ion is 7.5 degrees and etching from both left and right are equally strong. Therefore the sidewalls become nearly perpendicular. In a second example embodiment there may be up to +/- 30 degrees for less vertical side walls, but higher throughput since a larger angle range results in more of the ion beam may be utilized. A third example embodiment limits the angle range to less than 7.5 degrees for even more vertical sidewalls than the 15 degree range which is beneficial for accurate transfer of very deep patterns, e.g. high pyramids with sharp edges and tips. In a fourth example embodiment the trajectories of the particles are shaped by electric and/or magnetic fields to hit the cylinder more perpendicular over an extended angle range, thereby allowing a wider and faster etching beam to be used. In embodiments, larger angle ranges can be used with multiple etching heads.

[0035] Following an etching step, the patterned outer surface of the cylinder may be used for printing, embossing, or imprinting of a pattern on a workpiece which may be a foil or a sheet. In particular the workpiece may be a continuous foil running off one roll of material and on to another, roll-to-roll processing. Printing methods can also include heat embossing,

nanoimprinting, offset, reverse offset, flexo, and gravure printing.

[0036] As used herein, the terms ion beam and plasma etching is used to describe a flow of particles, which can be charged ions, molecular radicals, neutral atoms or protons, in a direction from a plasma towards the cylinder, and which particles etch the surface of the cylinder by a chemical reaction and/or by physical sputtering.

[0037] As discussed herein, seamless means that there is no gap, discontinuity, or local stitching error in the pattern on the cylinder and that an undetermined length of pattern with no gap or discontinuity can be produced on a foil by rolling the cylinder multiple turns, or at least more than one turn, against the foil while printing, embossing, or imprinting a pattern that is longer than the circumference of the cylinder.

[0038] Some particular implementations

[0039] The technology disclosed may be practiced as a method, device or system. One method. One method includes forming a 3D nano printing surface with non-binary features on a cylindrical form. The method may include building up a thick layer of resist over an exterior surface material of the cylindrical form, wherein the layer of resist over the exterior surface is built up to be 10 to 30 microns thick. The method may also include performing depth-based scaling of the non-binary features of a 3D latent image, wherein said depth-based scaling is proportioned to take into account a difference in etch rate between the resist and the surface material of the cylindrical form, thereby enabling a directional etching to proportionally transfer a 3D latent image onto the surface of the cylindrical form. The method may also include forming a seamless 3D latent image with said depth-based scaled non-binary features in the resist by exposing the resist to radiation as the cylindrical form rotates. The method may also include developing the 3D latent image to form 3D features in the developed resist. The method may also include directionally etching away the developed resist and the exterior surface of the cylindrical form to proportionally transfer the 3D, non-binary features onto the surface of the cylindrical form. [0040] This method and other implementations of the technology disclosed can each optionally include one or more of the following features and/or features described in connection with additional methods disclosed. In the interest of conciseness, the combinations of features disclosed in this application are not individually enumerated and are not repeated with each base set of features. The reader will understand how features identified in this section can readily be combined with sets of base features identified as implementations.

[0041] For example, building up the layer of resist may include applying the resist in multiple passes as the cylindrical form rotates, and during the applying, exposing the resist on the cylindrical form to an atmosphere containing solvent vapor in a proportion effective to avoid formation of a skin over applied resist prior to a subsequent pass of applying additional resist. Building up the layer of resist may also include applying the resist by lowering the cylindrical form into a reservoir of liquid resist, and removing the cylindrical form from the reservoir of liquid resist at a withdrawal speed and exposing the resist on the cylindrical form to an atmosphere containing solvent vapor, wherein the withdrawal speed and proportion of solvent vapor in the atmosphere are determined based on the desired resist thickness.

[0042] Regarding forming a seamless 3D latent image the method may include imaging a patterning onto the resist using a spatial light modulator. Measuring the cylindrical form and calculating a circumference of the cylindrical form may be used for scaling an intended latent image to the circumference before forming the seamless 3D latent image is formed. The scaling may further includes maintaining feature size of repeating primary features in the intended latent image and modifying spacing among the repeating primary features.

[0043] Performing directional etching may be done with a plasma projected through an aperture that limits an angle of incidence between the plasma and the layer of resist to vertical +/- 15 degrees. The directional etching may further be done with rotation of the cylindrical form around the axis of cylindrical form. Performing the directional etching may also include reciprocation of the cylinder along the axis of cylindrical form. Performing the directional etching may also be done one or more etching heads.

[0044] A system may include a resist application tool comprising, a chamber having a controlled atmosphere including solvent in a proportion effective to avoid formation of a skin over applied resist prior to a subsequent pass of applying additional resist and a sprayer that applies the resist in multiple passes to build up a thick layer of resist on a cylindrical form, wherein the layer of resist over the exterior surface is built up by said multiple passes to be 10 to 30 microns thick. The system may further include a patterning tool comprising a pattern controller configured to adjust an intended 3D latent image to match a circumference measured for the cylindrical form, wherein said pattern controller is further configured to perform depth- based scaling of non-binary features of a 3D latent image by taking into account a difference in etch rate between the resist and the surface material of the cylindrical form, said depth-based scaling is performed so that the intended 3D latent image can be proportionally transferred by directional etching onto the surface of the cylindrical form, and an exposing beam that projects radiant energy onto the layer of resist under control of the pattern controller to form a latent 3D image with repeating non-binary features in the layer of resist as the cylindrical form rotates. The system may further include a directional etching tool comprising a directional etcher that projects etchant onto the layer of resist, after development, as the cylindrical form rotates, and an aperture that restricts projection of the etchant to an angle of incidence between the plasma and the layer of resist that is within +/- 15 degrees of vertical.

[0045] The patterning tool may further comprise a spatial light modulator configured to modulate the exposing beam. The pattern controller may be configured to perform depth-based scaling including maintaining feature size of repeating primary features in the intended latent image and modifying spacing among the repeating primary features. The directional etcher may project etchant onto the layer of resist, after development, as the cylindrical form reciprocates along the axis of cylindrical form. The directional etcher may include a plurality of etching heads.

[0046] We claim as follows:

Claims

1. A method forming a 3D nano printing surface with non-binary features on a cylindrical form, including: building up a thick layer of resist over an exterior surface material of the cylindrical form, wherein the layer of resist over the exterior surface is built up to be 10 to 30 microns thick; performing depth-based scaling of the non-binary features of a 3D latent image, wherein said depth-based scaling is proportioned to take into account a difference in etch rate between the resist and the surface material of the cylindrical form, thereby enabling a directional etching to proportionally transfer a 3D latent image onto the surface of the cylindrical form; forming a seamless 3D latent image with said depth-based scaled non-binary features in the resist by exposing the resist to radiation as the cylindrical form rotates; developing the 3D latent image to form 3D features in the developed resist; and directionally etching away the developed resist and the exterior surface of the cylindrical form to proportionally transfer the 3D, non-binary features onto the surface of the cylindrical form.

2. The method of claim 1, wherein building up the layer of resist includes: applying the resist in multiple passes as the cylindrical form rotates; and during the applying, exposing the resist on the cylindrical form to an atmosphere containing solvent vapor in a proportion effective to avoid formation of a skin over applied resist prior to a subsequent pass of applying additional resist.

3. The method of claim 1, wherein building up the layer of resist includes: applying the resist by lowering the cylindrical form into a reservoir of liquid resist; and removing the cylindrical form from the reservoir of liquid resist at a withdrawal speed and exposing the resist on the cylindrical form to an atmosphere containing solvent vapor, wherein the withdrawal speed and proportion of solvent vapor in the atmosphere are determined based on a desired resist thickness.

4. The method of claim 1 , wherein forming a seamless 3D latent image includes: imaging a patterning onto the resist using a spatial light modulator.

5. The method of claim 1, further including: measuring the cylindrical form and calculating a circumference of the cylindrical form; and scaling an intended latent image to the circumference before forming the seamless 3D latent image.

6. The method of claim 5, wherein the scaling further includes maintaining feature size of repeating primary features in the intended latent image and modifying spacing among the repeating primary features.

7. The method of claim 1, further including performing the directional etching with a plasma projected through an aperture that limits an angle of incidence between the plasma and the layer of resist to vertical +/- 15 degrees.

8. The method of claim 1, further including performing the directional etching with rotation of the cylindrical form around the axis of the cylindrical form.

9. The method of claim 1, further including performing the directional etching with reciprocation of the cylinder along the axis of the cylindrical form.

10. The method of claim 1, further including performing the directional etching with a plurality of etching heads.

11. A cylindrical form patterning system, including: a resist application tool comprising: a chamber having a controlled atmosphere including solvent in a proportion effective to avoid formation of a skin over applied resist prior to a subsequent pass of applying additional resist; and a sprayer that applies the resist in multiple passes to build up a thick layer of resist on a cylindrical form, wherein the layer of resist over an exterior surface is built up by said multiple passes to be 10 to 30 microns thick; a patterning tool comprising: a pattern controller configured to adjust an intended 3D latent image to match a circumference measured for the cylindrical form, wherein said pattern controller is further configured to perform depth-based scaling of non-binary features of a 3D latent image by taking into account a difference in etch rate between the resist and surface material of the cylindrical form, said depth-based scaling is performed so that the intended 3D latent image can be proportionally transferred by directional etching onto the surface of the cylindrical form; and an exposing beam that projects radiant energy onto the layer of resist under control of the pattern controller to form a latent 3D image with repeating non-binary features in the layer of resist as the cylindrical form rotates; an a directional etching tool comprising: a directional etcher that projects etchant onto the layer of resist, after development, as the cylindrical form rotates; and an aperture that restricts projection of the etchant to an angle of incidence between the etchant and the layer of resist that is within +/- 15 degrees of vertical.

12. The cylindrical form patterning system of claim 11, wherein patterning tool further comprises a spatial light modulator configured to modulate the exposing beam.

13. The cylindrical form patterning system of claim 11, wherein the pattern controller is further configured to perform depth-based scaling including maintaining feature size of repeating primary features in the intended latent image and modifying spacing among the repeating primary features.

14. The cylindrical form patterning system of claim 11, wherein the directional etcher projects etchant onto the layer of resist, after development, as the cylindrical form reciprocates along the axis of the cylindrical form.

15. The cylindrical form patterning system of claim 11, wherein the directional etcher includes a plurality of etching heads.