Micro/nano functional structure manufacturing from difficult-to-cut materials by etching and its combined machining strategies: A review

Micro/nano functional structures (MNFSs) have attracted substantial attention because of their outstanding performance in optical, tribological, thermal, electronic, and biomedical applications. Despite the development of various mechanical and non-mechanical machining methods, achieving the high-efficiency, high-precision fabrication of MNFS from difficult-to-cut materials remains a significant technical challenge. This review begins with an introduction to typical artificial MNFSs and their stringent requirements and then provides a comprehensive survey of MNFSs, focusing on etching methods. In particular, plasma etching demonstrates notable advantages in MNFS fabrication. However, two critical challenges persist: accurately controlling topographical information during pattern transfer in plasma etching and achieving high-quality, uniform patterning masks over large areas. These issues are addressed by thoroughly analyzing and summarizing the modeling of plasma etching and the simulation of feature profiles. Various hybrid etching machining (HEM) strategies, including laser and etching combined machining, cutting and etching combined machining, molding and etching combined machining, and self-assembly and etching combined machining, are categorized and compared in detail to facilitate the manufacturing of complex MNFSs. Finally, this review summarizes current deficiencies and future challenges of HEM, laying the groundwork for further advancements in MNFS fabrication and intelligent HEM technologies.