Technical Note: High-Precision Micromachining

By IMRA America, Inc.

Laser micromachining is a large and rapidly-growing application area for pulsed lasers. In fact, the general application area of materials processing forms the largest single application market for all lasers sold. Laser micromachining, as a subset of materials processing, is used in many industry sectors including automotive, medical device manufacturing, printing, marking, and electronics. Microelectronics in particular is one of the largest industry sectors that uses laser micromachining for a variety of applications including mask repair, chip repair, linkblowing, wafer processing, via-hole drilling and others. Pulsed lasers that are widely used include excimer lasers and Qswitched solid-state lasers such as Nd:YAG and Vanadate systems.

These conventional types of micromachining lasers typically produce pulses with durations of nanoseconds to microseconds. In the last several years however, femtosecond lasers have shown great promise to improve the quality and reduce the scale of fine detail which can be obtained by laser micromachining. The unique ablation properties of femtosecond lasers render higher precision in micromachining with reduced thermal effects, as well as a reduction in debris, recast, and burring. Additionally, they allow easier cutting and drilling of transparent materials with less collateral damage to the workpiece. This opens up possibilities to either replace conventional lasers in some applications, but even more interesting is the variety of new emerging applications that will be enabled by these unique capabilities. For example, these unique processing capabilities are being exploited in the semiconductor industry as well as the field of ophthalmic surgery.