A study of 355nm DPSS UV laser micromaching for silicon wafer

Abstract

In recent years, laser micromachining of semiconductor materials such as silicon and sapphire has attracted more and more attention. High accuracy cutting and drilling technology has been successfully used in semiconductor, optoelectronics and MEMS industries, including wafer dicing, punching and 3D structuring. The high power diode pumped solid state UV laser with high efficiency, high repetition rate, highly flexibility, high dependability, minisize, excellent beam quality and good power stability shows a obvious advantage in the field of micromachining. The source we use in this study is a 10W, 355nm DPSS Nd: YVO4 laser. The optical system consists of a beam expander, a scan head, an f-θ lens and a short focus lens. The micromachining table is driven by two orthogonal linear induction motors, with the precision and the repetition precision are both ±1µm. The effect of the process parameters such as laser power density, repetition rate, scanning speed and pulse energy on the diameter, depth and quality of silicon drilling, as well as the width, processing efficiency and quality of dicing are studied in detail. When the maximum depth-width ratio is needed, the optimal process parameters is about: laser power of 5.4W, frequency of 80k Hz, scanning speed 150mm/s. Using the optimal process parameters, direct forming process of the three thicknesses of silicon are carried out, small heat-affected zone, little flying objects, and no cracks are occurred.In recent years, laser micromachining of semiconductor materials such as silicon and sapphire has attracted more and more attention. High accuracy cutting and drilling technology has been successfully used in semiconductor, optoelectronics and MEMS industries, including wafer dicing, punching and 3D structuring. The high power diode pumped solid state UV laser with high efficiency, high repetition rate, highly flexibility, high dependability, minisize, excellent beam quality and good power stability shows a obvious advantage in the field of micromachining. The source we use in this study is a 10W, 355nm DPSS Nd: YVO4 laser. The optical system consists of a beam expander, a scan head, an f-θ lens and a short focus lens. The micromachining table is driven by two orthogonal linear induction motors, with the precision and the repetition precision are both ±1µm. The effect of the process parameters such as laser power density, repetition rate, scanning speed and pulse energy on the diameter, depth and quality ...