Ultrafast laser micromachining of wide-bandgap semiconductor materials such as silicon carbide (SiC), gallium nitride (GaN), and aluminum nitride (AlN) offers significant potential for fabricating next-generation electronic and photonic devices. However, precise control over small-scale geometries remains challenging due to the material’s high hardness, low fracture toughness, and nonlinear absorption, as well as the coupled plasma and thermomechanical effects during processing. Conventional galvanometer-based scanning approaches with a fixed angle of incidence are limited in their ability to produce high-aspect-ratio structures with controlled sidewall morphology. In particular, achieving such features requires simultaneous control of beam position, focal depth, and angle of incidence during ultrafast laser processing.

   In this study, as a model system, semiconductor substrates including silicon and wide-bandgap materials of varying thickness were processed using a femtosecond infrared laser integrated with a 5-axis micromachining subsystem (precSYS SCANLAB). The system enables dynamic control of beam position, focal depth, and divergence through coordinated galvanometer-based beam steering, allowing independent adjustment of lateral position (x–y), focal position (z), and angle of incidence (ϴx, ϴy).

   For initial characterization, micromachining was performed under fixed beam position with normal angle of incidence to establish relationships between process parameters and feature morphology. Subsequently, various beam trajectories, including circular, rectangular, helical, and spiral were performed with dynamically varying incidence angles and focal positions. By systematically varying beam position and angle of incidence, feature morphology was effectively controlled, resulting in reduced taper and improved sidewall profile. These findings provide insights into beam control strategies for high-precision semiconductor micromachining.