Cut-Off UV Light Filter to Prevent the Negative Slope of the Soft Lithography Hard Mold Walls

• Published in: Russian microelectronics 2022-12, Vol.51 (7), p.539-544
• Main Authors: Radzievskaya, T. A., Ivanov, N. N., Tarasov, S. A.
• Format: Article
• Language: English
• Subjects: Circuit boards; Electrical Engineering; Electromagnetic wave filters; Engineering; Luminous intensity; Manufacturing; Mercury lamps; Nanolithography; Optical radiation; Optical waveguides; Optoelectronics; Photoresists; Polymers; Printed circuit boards; Printed circuits; Radiant flux density; Thickness; Topology; Ultraviolet filters; Ultraviolet radiation; Wavelengths
• ISSN: 1063-7397; 1608-3415
• DOI: 10.1134/S1063739722070174

To solve the problem of shaping nonspecialized polymers, new generation micro- and nanoelectronic technologies are used, for example, nanoimprint lithography. A special case of nanoimprint lithography is soft lithography, which involves the formation of a topology using a soft master mold fabricated by a hard mold imprint. Therefore, the study of hard molds self-manufacturing possibility is an urgent task to fabricate a new generation printed circuit boards with optoelectronic buses made of nonspecialized polymer materials. In order to rationalize the cost of purchasing an expensive soft lithography hard mold, an original technological process for hard mold fabrication based on an SU-8 photoresist is developed and implemented. During the development of the proposed technological process, the reason for the formation of a negative slope (T-topping) of the walls of the soft lithography hard mold is determined. In order to eliminate the negative slope, a series of UV cutoff filters for optical radiation wavelengths less than 350 nm is developed and manufactured. According to the experimental measurements data of the i -line mercury lamp UV radiation intensity of the EVG620 NIL automated alignment and exposure unit, the dependences of the UV radiation intensity attenuation on the developed UV light filter functional layer thickness are plotted for 365 and 400 nm optical wavelengths. The effectiveness of the use of the developed UV filters is proved by eliminating the negative slope during the technological process of manufacturing a test topology of the soft lithography hard mold. Soft lithography will make it possible in the future to create printed circuit boards with a built-in optoelectronic data bus in the form of an array of polymer planar optical waveguides and optical input-output elements.