Contrast enhancement behavior of hydrogen silsesquioxane in a salty developer

Abstract

The authors investigated a contrast enhancement behavior of hydrogen silsesquioxane ͑HSQ͒ in a salty development system ͑NaOH / NaCl͒. Time-resolved analysis of contrast curves and line-grating patterns were carried out to investigate the unique properties of a salty development process. In NaOH developer without salt, the development process was saturated beyond a certain development time. On the other hand, the addition of salt enabled a continuous development, which was not observed in the pure NaOH development. The continuous thinning process enhances the contrast of HSQ in the salty developer, which allows a fast collapsing behavior in HSQ line-grating patterns. During development process, salt seems to have the role of modifying HSQ by breaking network bonds preferentially, leading to a continuous development rate.

Understanding of hydrogen silsesquioxane electron resist for sub-5-nm-half-pitch lithography

“…This result suggests that a high initial development rate might be an important indicator of good developer performance. Recent results 14 have also shown a later-stage ͑ Ͼ 10 min͒ thinning effect that occurred only in the salty development. However, we did not observe such effects in the experiments reported in this article possibly due to differences in processing conditions, such as the total processing time, which was 3 days in our case compared to 1 day in Ref.…”

Nanopillar and nanohole fabrication via mixed lithography

“…Electron beam lithography (EBL) is a proven method for the highly accurate fabrication of sub-100 nm structures [1][2][3][4][20][21][22][23][24][25][26]. However, due to its high costs and low throughput, the use of EBL has been limited for producing nano-scale patterns in the extremely localized area.…”

Electrochemical development of hydrogen silsesquioxane by applying an electrical potential

“…Also, slight swelling of the remaining material has been reported [8]. The second category includes developers based on alkaline solutions like tetramethyl-ammonium hydroxide (TMAH), potassium hydroxide (KOH), or sodium hydroxide (NaOH) [9,10,1]. In an alkaline solution, the resist molecules undergo an ionization process comparable to an acidic reaction.…”

“…Several methods have been studied that reduce footing and increase contrast. Development in more highly concentrated alkaline solution [12], at higher Preprint for Nanotechnology Full article available at http://iopscience.iop.org/0957-4484/22/37/375301/ Page 4 of 17 development temperatures [13,14] , , and with added salts [15,14,10,16], all increase the developer contrast. As described by Kim et al, the added salt ions can weaken Si-O bonds of partially cross-linked HSQ.…”