Nanoscale Pattern Transfer by Deposition

Another type of pattern transfer is by thin film deposition, which is an additive process opposite to subtractive etching. In this fabrication process, the way how the thin film is deposited plays a key role. This chapter starts with an overview of thin film deposition technology and emphasizes the importance of deposition directionality on the successful liftoff of film from a patterned resist mask. Although thermal evaporation deposition has good directionality suitable for liftoff, sputtering deposition provides better quality of thin film albeit its poor directionality which can be remedied by a multilayer resist system as introduced in the chapter. In addition to liftoff, the chapter also introduces electroplating as an additive pattern transfer technique, which is particularly suitable to produce high aspect ratio pattern structures. Its relevance to making interconnects in integrated circuit manufacturing is emphasized. In addition to aforementioned two techniques, pattern transfer through stencil masks and pattern formation by direct printing are also presented.