Beam shaping applications in laser micromachining for the microelectronics industry

摘要

Laser micromachining has been a part of the manufacturing process for semiconductors and microelectronics devices for several decades. More recent applications such as the drilling of microvia holes in high-density electronic packages have recently entered broad industrial use for high-volume production. In such applications, process stability and throughput are key drivers of commercial success. Particularly in the UV, where solid-state laser power is growing rapidly but is still limited to less than 10 watts, innovations that permit the available laser power to be applied at the work surface more efficiently are of interest. Within the last two years, the use of beam shapers to create round laser spots with near-uniform irradiance at the work surface has been demonstrated. Shaping the irradiance profile has been shown to both increase process speed and improve the quality of the drilled holes, which range in diameter between 20 and 150 μm. This paper gives an historical overview of laser via drilling, presents the Gaussian-to-flattop beam shaping optics used in the microvia laser drills, and discusses the process results obtained.