Semiconductor micro/nano fabrication involves many core processes, and it is difficult to define a single step as the only “core.” Lithography, etching, deposition, doping, planarization and metrology must work together to convert design patterns into functional devices.

Lithography is often called the leading process because it defines pattern resolution and alignment. It determines where structures will be formed and sets the foundation for subsequent etching and deposition. Without accurate lithography, the rest of the process cannot faithfully reproduce the design.

Etching is the key process that transfers lithography patterns into physical materials. It determines sidewall shape, depth, selectivity and surface quality. For advanced semiconductors and MEMS devices, etching accuracy directly affects electrical, optical and mechanical performance.

Thin-film deposition builds the functional layers required for devices, including metal interconnects, dielectric layers, barrier layers, electrodes and sensing films. Deposition quality affects film uniformity, stress, adhesion and reliability.

In practice, the core of semiconductor micro/nano fabrication is process integration. Lithography must match etching capability; deposition must be compatible with existing layers; cleaning, inspection and planarization must maintain yield. A weakness in any single step may affect the entire device.

Therefore, rather than viewing one process as the absolute core, semiconductor micro/nano fabrication should be understood as a coordinated system. The ability to integrate multiple processes reliably is what determines manufacturing success.