Pattern transfer into silicon using sub-10 nm masks made by electron beam-induced deposition

To demonstrate the possibility of using electron beam-induced deposition (EBID) masks for sub10 nm pattern transfer into silicon, first experiments were carried out by using 20- to 40-nm EBID masks, which were etched by different chemistries. It is experimentally verified that recipes based on hydrogen bromide, chlorine, and boron trichloride can selectively etch silicon when using 20- to 40-nm masks made by EBID. We observed an enhancement of the height ratio, i.e., the ratio of the height of structures before and after etching, up to a factor of 3.5 when using chlorine chemistry. To demonstrate the pattern transfer of sub-10 nm structures, further experiments were carried out using 8- to 20-nm EBID masks in combination with hydrogen bromide, chlorine, and fluorine chemistries. Fluorine chemistry provided the best results in terms of surface smoothness and height ratio. In this case, 7.4-nm lines were successfully transferred into silicon, resulting in 14.3-nm-wide lines with a height ratio of similar to 5. (C) 2015 Society of Photo-Optical Instrumentation Engineers (SPIE)