Ablation and cutting of planar silicon devices using femtosecond laser pulses
Ablation and cutting of planar silicon devices using femtosecond laser pulses
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DOI：
10.1007/s00339-003-2118-4
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发表时间：
2003-07-01
影响因子：
2.7
通讯作者：
Tönshoff, KH
中科院分区：
文献类型：
--
作者：
Bärsch, N;Körber, K;Tönshoff, KH
虽然激光通常能够加工硅，但在许多微系统应用中的主要材料，在不影响大块材料的物理特性的情况下这样做仍然是一个重要的挑战。特别是超快激光器，具有精确烧蚀各种固体材料的潜力，能够以高效率和高精度执行此类过程。本文首先概述了超快激光辐射与半导体的一般相互作用，解释了硅烧蚀的吸收过程和不同的注量制度。主要参数的影响，特别是在薄硅切割过程中，进行了说明。通过改变脉冲能量、光束整形方法、光束偏振和温度，切割质量和速度会受到显着影响。除了切口宽度和表面粗糙度之外，一个重要的质量方面是切割脆性材料时的背面碎屑量。使用线性聚焦形状的速度提高的成就，与切割速度高达五倍以上，比传统的点聚焦。另一方面，采用点聚焦切割的激光工艺提供了自由形状切割的可能性，这一点将以承载封装密度大幅提高的硅芯片的晶圆为例进行说明。
Although lasers are generally able to machine silicon, the major material in many microsystems applications, doing so without influencing the physical properties of the bulk material remains an important challenge. Ultrafast lasers, in particular, with their potential to precisely ablate all kinds of solid materials, are able to perform such processes with high efficiency and accuracy. This article starts with an overview of the general interaction of ultrafast laser radiation with semiconductors, explaining the absorption processes and different fluence regimes for the ablation of silicon. Major parameter influences, especially for cutting processes in thin silicon, are described. By varying pulse energies, beam shaping methods, the beam polarization, and temperatures, the cutting quality and speed can be significantly influenced. One important quality aspect, besides kerf widths and surface roughness, is the amount of back-side chipping when cutting brittle materials. Achievements in speed enhancement using linear focus shapes are presented, with cutting speeds up to five times higher than by conventional spot-focusing. On the other hand, laser processes that cut with a spot focus offer the possibility of free-shape cutting, which is explained using the example of wafers carrying silicon chips with highly increased package densities.