Shape control of polymer reflow structures fabricated by nanoimprint lithography

Schift, Helmut; Spreu, Christian; Schleunitz, Arne; Lee, Jaejong

doi:10.1016/j.mee.2010.08.029

Cited by 34 publications

(25 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…An interesting correlation for the formation of dots was found in the first experiments with surfactant coated ridges, 5 which was based on the assumption, that coagulation is directly linked to the tendency of a polymer ridge to spread on a hydrophobic substrate. For a substrate with hydrophobic properties, this would happen if the aspect ratio exceeds the factor of 0.25.…”

Section: Resultsmentioning

confidence: 96%

“…This process is well described in some of our previous publication. 5 ing, the structures were thinned down and substrate windows were opened by anisotropic RIE using oxygen plasma. As a hydrophobic coating, we applied our standard MVD process at room temperature directly after the RIE process.…”

Section: Methodsmentioning

confidence: 99%

“…However, for ridges with a line width of 100 nm, we then observe a dewetting of resist during reflow. 5 The resist, which normally tends to spread laterally to some extent over the areas covered by the surfactant, splits locally and collects material along the ridges to form larger hemispherical dots. Since the material is not able to flow large distances, local depletion happens and dots are formed along the lines which are almost randomly distributed ͓see schematic in Fig.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Fabrication of ordered nanospheres using a combination of nanoimprint lithography and controlled dewetting

Schleunitz

Spreu

Lee

et al. 2010

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

Self Cite

View full text Add to dashboard Cite

Arrays with hemispherical dots were produced from nanoimprinted line structures by thermal reflow and coagulation. By adding local nodes into 100 nm wide line cavities of the nanoimprint stamp, the coagulation was controlled and a self-ordered, highly regular dot matrix with almost totally dewetted lines was obtained. The forming of dots of almost equal sizes and distances along the line’s location shows that this coagulation effect is probably only restricted by geometry and surface energy. Simple resist preforms can be transformed into a more complex pattern by thermal-postprocessing in a controlled way.

show abstract

Section: Resultsmentioning

confidence: 96%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Fabrication of ordered nanospheres using a combination of nanoimprint lithography and controlled dewetting

Schleunitz

Spreu

Lee

et al. 2010

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

Self Cite

View full text Add to dashboard Cite

show abstract

“…For example, a line of fluid on a non-wetting substrate undergoes a PlateauRayleigh instability that breaks the line into droplets. Recent experiments have shown that the resulting droplets can be organized by an initial modulation of the line [23,24]. However, in these particular studies, the residual layer between the lines was first removed by an etching step before any annealing.…”

Section: Introductionmentioning

confidence: 99%

Dewetting of the residual layer of annealed nanoimprinted polystyrene films

Rognin

Landis

Davoust

2015

Microelectronic Engineering

View full text Add to dashboard Cite

International audienceThe presence of a residual layer at the end of a classical NanoImprint Lithography (NIL) process is at the root of many issues when NIL is used to manufacture resist patterns used later as an etching mask. In this paper, we investigate how the spontaneous break-up of annealed polystyrene films, a phenomenon called dewetting, can produce residual-layer-free polymer patterns. Although the dewetting of flat polymer films has been characterized for decades, little interest has been focused on patterned films. We present exploratory experiments conducted on polystyrene 30 kg/mol ultra-thin films. The samples are embossed using thermal NIL with a specific spatially modulated space/line patterned mold, and then annealed at 50 degrees C above the glass transition temperature. The resulting patterns are then interpreted as a competition between surface tension and van der Waals forces. Finally, a quantitative analysis is made in the framework of lubrication theory, with the help of a finite volume simulation tool

show abstract

“…As an alternative, thermal reflow is widely used to generate microlenses with smooth surfaces for optical applications. Spherical surfaces result from the fact that surface tension tends to minimize surfaces and therefore results in convex refractive lenses defined by the outlines and height of the original binary resist structure alone [1,2]. The diversity of 3-D shapes, e.g.…”

mentioning

confidence: 99%

Fabrication of Stepped and Reflowed 3-D Profiles for Optical Applications by Dose-modulated Electron Beam Lithography and Selective Thermal Reflow

Schift

Schleunitz

2011

CLEO:2011 - Laser Applications to Photonic Applications

Self Cite

View full text Add to dashboard Cite

Microlens and prism arrays were fabricated using multi-level electron beam patterning combined with thermal reflow. The molecular weight dependent processing allows selective transfer of stepped into sloped resist structures with smooth surfaces.Optical elements with combined diffractive and refractive properties often need surfaces with 3-D profiles, e.g. lenses and prisms, in addition to binary gratings with defined box-type ridges. Normally these elements can only be achieved by the combination of different lithographic steps or with grayscale techniques based on dose-modulated optical or electron beam lithography (DM-EBL) with its limited ability to approximate arbitrary shapes with smooth surfaces. As an alternative, thermal reflow is widely used to generate microlenses with smooth surfaces for optical applications. Spherical surfaces result from the fact that surface tension tends to minimize surfaces and therefore results in convex refractive lenses defined by the outlines and height of the original binary resist structure alone [1,2]. The diversity of 3-D shapes, e.g. prisms with linear slopes and sharp features, lenses with arbitrary convex and concave profiles, or combinations of both, is very restricted. We have now combined DM-EBL with thermal reflow. Starting from 3-D multi-level structures in high molecular weight M w poly(methyl methacrylate) (PMMA) resist, reflow at a moderate temperature does not lead to the formation of the spherical forms defined by surface tension, but profiles matching that of the original stepped structure and with smooth outlines. A multi-level step structure with only a few steps can be easily transferred into a linear slope, simply by smoothening out the surface undulations given by the steps, resulting from lithographically defined local variations of M w [3]. Fig. 1. Process chain or schematic: 3-D resist shapes are achieved by dose-modulated EBL and development. Sharp staircase profiles can be transformed into continuous surface reliefs by thermal annealing at T ~Tg while vertical sidewalls stay unaltered.The main difference to normal reflow is, that local difference in glass transition temperature T g caused by M w reduction in exposed areas can be used to selectively transfer exposed stepped structures into continuous slopes during thermal reflow, while other structures with vertical sidewalls stay unaltered. Prism structures with slopes with 1 µm height and up to 45° inclination were generated using different combinations of doses and reflow temperatures. A variety of slope angles and orientations can be fabricated on the same substrate. Fig. 2. Micrographs of multi-level resist structure (left side, 520 nm high PMMA) with 4-levels of 0.5 µm step size transformed into a structure with sloped sidewalls (right side) with 2 µm slope by thermal post-processing (mid section shows an intermediate reflow state).

show abstract

Shape control of polymer reflow structures fabricated by nanoimprint lithography

Cited by 34 publications

References 24 publications

Fabrication of ordered nanospheres using a combination of nanoimprint lithography and controlled dewetting

Fabrication of ordered nanospheres using a combination of nanoimprint lithography and controlled dewetting

Dewetting of the residual layer of annealed nanoimprinted polystyrene films

Fabrication of Stepped and Reflowed 3-D Profiles for Optical Applications by Dose-modulated Electron Beam Lithography and Selective Thermal Reflow

Contact Info

Product

Resources

About