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Proceedings Paper

Wafer dicing utilizing unique beam shapes
Author(s): Todd Lizotte; Orest Ohar
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Paper Abstract

Laser dicing of wafers is of keen interest to the semiconductor and LED industry. Devices such as ASICs, Ultra-thin Wafer Scale Packages and LEDS are unique in that they typically are formed from various materials in a multilayered structure. Many of these layers include active device materials, passivation coatings, conductors and dielectric films all deposited on top of a bulk wafer substrate and all potentially having differing ablation thresholds. These composite multi-layered structures require high finesse laser processes to ensure yields, cut quality and low process cost. Such processes have become very complex over the years as new devices have become miniaturized, requiring smaller kerf sizes. Of critical concern is the need to minimize substrate micro-cracking or lift off of upper layers along the dicing streets which directly corresponds to bulk device strength and device operational integrity over its projected lifetime. Laser processes involving the sequential use of single or multiple diode pumped solid state (DPSS) lasers, such as UV DPSS (355nn, 266nm, 532 nm), VIS DPSS (~532 nm) and IR DPSS (1064nm, 1070nm) as well as (UV, VIS, NIR, FIR and Eye Safe Wavelengths) DPFL (Diode Pumped Fiber Lasers) lasers to penetrate various and differing material layers and substrates including Silicon Carbide (SiC), Silicon, GaAs and Sapphire. Development of beam shaping optics with the purpose of permitting two or more differing energy densities within a single focused or imaged beam spot would provide opportunities for pre-processing or pre-scribing of thinner cover layers, while following through with a higher energy density segment to cut through the bulk base substrates. This paper will describe the development of beam shaping optical elements with unique beam shapes that could benefit dicing and patterning of delicate thin film coatings. Various designs will be described, with processing examples using LED wafer materials.

Paper Details

Date Published: 12 September 2007
PDF: 9 pages
Proc. SPIE 6663, Laser Beam Shaping VIII, 66630L (12 September 2007); doi: 10.1117/12.732129
Show Author Affiliations
Todd Lizotte, Hitachi Via Mechanics USA, Inc. (United States)
Orest Ohar, Hitachi Via Mechanics USA, Inc. (United States)

Published in SPIE Proceedings Vol. 6663:
Laser Beam Shaping VIII
Fred M. Dickey; David L. Shealy, Editor(s)

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