Thermal imprint with negligibly low residual layer

Abstract

Thermal imprint into polymer layers that are thin compared to the pattern height allows for imprints with extremely low and uniform residual layers where lift-off works without previous dry etching. The authors report about possible restrictions of this method such as unintended self-assembling and recovery of polymer underneath the imprinted structures. Both can be attributed to structure size properties and temperature influence and hinder a subsequent successful lift-off. Taking the example of two different temperatures and two different initial layer thicknesses the authors investigate their impact on the resulting structure shape and potential defects. In addition, to qualitatively estimate the residual layer thickness the authors apply lift-off and discuss the results with focus on the usability of this approach as a lithography technique.

Reversed order hybrid lithography of T-NIL and UVL

“…Most probably these line ends are almost without contact to the underlying Si. Defect-free imprint under partial cavity filling requires a temperature compromise [13] -with AZ 1505 this situation was met at 130°C: The viscosity is low enough to imprint through but still high enough to avoid defects from physical self-assembly (with other imprint materials the optimum temperature may be different). Fig.…”

Investigation of the separation of 3D-structures with undercuts

“…2a. As observed also during thermal imprint of polymers at high temperature, completely filled sections alternate with unfilled sections within the linear cavities [7]. As highlighted by the inserted cross-section, wetting of the edges occurs first, resulting in thin filaments between the filled regions after curing.…”

Microstructuring of dual damascene opening by using hot-embossing combined with etch-back process

“…After embossing, the layer thickness was about 12 )tm (the half of master pattern height) more increased due to the accumulation of parylene-C underneath the embossed structures. To overcome this problem, the parylene-C layer that was thinner than master pattern height was adopted, considering the thickness increase of residual layer during hot-embossing [2]. Etch-back tests of the embossed parylene-C/Si samples were performed by using reactive ion etching (RIE) for varying pressure, gas flow, power, and etching chemistries (02, 02/SF6, 02/CHF3).…”