US Patent 7887712 Laser machining system and method

A substrate (16) is machined to form, for example, a via. The substrate is in a chamber (15) within which the gaseous environment is controlled. The machining laser beam (13) is delivered with control of parameters such as pulsing parameters to achieve desired effects. The gaseous environment may be controlled to control integral development of an insulating lining for a via, thereby avoiding the need for downstream etching and oxide growth steps. Also, machining may be performed in multiple passes in order to minimize thermal damage and to achieve other desired effects such as a particular via geometry.