Impact of laser scribing for efficient device separation of LED components

Illy, Elizabeth K.; Knowles, M. R. H.; Gu, Erdan; Dawson, Martin D.

doi:10.1016/j.apsusc.2004.12.033

Cited by 21 publications

(14 citation statements)

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“…If designed correctly, the lower energy lobe can be utilized to remove lower ablation threshold materials or thin films through a liftoff technique or shockwave technique. [4] The optical element demonstrated an optical efficiency of ~92%, measured power, pre and post shaper.…”

Section: Optimized Zero Order Testingmentioning

confidence: 99%

“…This is sometimes a function of a low ablation threshold due to the material having a high absorption. [4] This technique is especially well-matched for patterning brittle thin film materials. Because this design was based on a eight level binary design its efficiency was ~80%, measured power, pre and post shaper.…”

Section: Narrow Rectangular Kerf Designmentioning

confidence: 99%

“…This type of design is very efficient at >91%, with diffraction efficiency being defined here as the system throughput for all of the orders. The non-uniformity is defined as follows: ( 4 ) This is a typical flat top beam shaper that would provide a uniform spot size at a desired target or dicing image plane or intra-plane, but with a limited spot size.…”

Section: Revisiting Our Friend the Flat Top Shapermentioning

confidence: 99%

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Structured beam shaping for precision laser dicing of multilayered substrates

Ohar

2007

SPIE Proceedings

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Laser dicing of wafer based devices; such as light emitting diodes (LEDs) is multifaceted since these devices are formed from various materials in a layered 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 different ablation thresholds. These composite multi-layered structures require high finesse laser processes to ensure yields, high quality and low cost. Such processes have become very complex over the years as new devices become miniaturized, requiring smaller micro-machined features, greater precision and reduction of thermal stress to minimize substrate micro-cracking and maintain device integrity over its projected lifetime. Newer laser processes often involve the sequential use of single or multiple diode pumped solid state (DPSS) lasers, such as UV DPSS (355nn, 266nm), VIS DPSS (~532 nm) and IR DPSS (1064nm, 1070nm) as well as DPFL (Diode Pumped Fiber Lasers) lasers to penetrate various and differing material layers and substrates including SiC, Silicon 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 portion to cut through base substrates. This technique is also possible using multiple wavelengths simultaneously for micro-machining or dicing. Using multiple wavelengths offers advantages where high photon energies from such wavelengths as 266 nm can cause adverse effects to doped materials such as silicon or to active device layers such as GaN or other III-V materials deposited on the substrate surface. This paper will describe the development of variable intensity beam shaping optical elements targeting micromachining, dicing and patterning of delicate thin film coatings. Various diffractive and holographic optic designs will be described, with examples, including select functional testing of the optics and examples of the optics use in laser micromachining various materials.

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Section: Optimized Zero Order Testingmentioning

confidence: 99%

Section: Narrow Rectangular Kerf Designmentioning

confidence: 99%

Section: Revisiting Our Friend the Flat Top Shapermentioning

confidence: 99%

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Structured beam shaping for precision laser dicing of multilayered substrates

Ohar

2007

SPIE Proceedings

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“…The figure indicates reduction in the maximum current after laser scribing for both UV wavelengths(Gu et al 2004;Illy et al 2005) Fig. 7.31 SEM image illustrating the quality of ∼25 µm deep scribe of LED components on sapphire substrate using 255 nm UV laser.…”

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confidence: 99%

Laser Fabrication and Machining of Materials

2008

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except for brief excerpts in connection with reviews or scholarly analysis. Use in connection with any form of information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now know or hereafter developed is forbidden. The use in this publication of trade names, trademarks, service marks and similar terms, even if they are not identifi ed as such, is not to be taken as an expression of opinion as to whether or not they are subject to proprietary rights.Printed on acid-free paper. 9 8 7 6 5 4 3 2 1 springer.com v medicine, it is rapidly making headways in the field of biomedicine. As mentioned earlier, Part I provides sufficient basics of lasers and laser processes to spawn thoughts in one's mind for new applications of lasers. Examples of such new applications are described in chapters on laser interference processing, laser shock processing, and laser dressing of grinding wheels. It is hoped that the book will provide further impetus to many more readers to take lasers into new frontiers of applications.Thus, unlike many other books on similar topics, this book deals with the subject of laser-based fabrication and machining in a comprehensive manner. The subject matter in the proposed book extends over a wide range of disciplines that include, but are not limited to, mechanical, electrical/electronics, materials, and manufacturing. Such interdisciplinary discussion of the topic is a need of the time for many undergraduate and graduate academic programs and research activities that themselves are increasingly wielding interdisciplinary flavor. Furthermore, the scope of the subject matter ranging over macro-, to micro-, to nanolevels of processing/ manufacturing is very important to educate and prepare individuals for the next generation manufacturing. In addition, the integration of fundamental principles and physical phenomena governing laser-based fabrication/machining processes and their existing and potential applications have widened the scope of the book across the sectors of academia, research, and industry.

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“…In the first case, it is a thermal process based on absorption of light by the substrate. Traditionally, the industrial dicer's use nanosecond pulses either with a wavelength of 355 nm scribing a line, colloquially called "the kerf", across the back surface of the wafer or a wavelength of 266 nm for cutting from the face of it [6][7][8][9]. However, this method produces a huge amount of debris.…”

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confidence: 99%

Stealth dicing of sapphire wafers with near infra-red femtosecond pulses

et al. 2017

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Mohs hardness index of ∼9) [3], and these properties make sapphire dicing a challenging affair.The mechanical separation of micro-devices, sometimes called "chips", using a diamond saw (diamond scribing) was the first technology used for chip separation and this technique was also a common choice to perform dicing of sapphire substrates. Since scribing is a contact process, there are critical issues of debris, delamination, chipping and heating of the wafer because of friction. Furthermore, diamond scribing is slow, produces a wide kerf with a width typically between ∼100 and 200 μm and has a low yield [4]. What is more, the quality of the surface (see Fig. 1a) after sawing is not acceptable even for light emitting diodes (LEDs).The laser-based technologies for dicing are based on light-matter interactions and can be grouped into two types: laser scribing and the stealth dicing. These technologies resolve many of the drawbacks of diamond scribing and today they are the prevalent processes used by LED manufacturers. These laser-based technologies offer non-contact, high-speed dicing, improving both the processing time and the chip density on a wafer [5].Laser scribing can be performed either by nanosecond or femtosecond pulses (see Fig. 1b). In the first case, it is a thermal process based on absorption of light by the substrate. Traditionally, the industrial dicer's use nanosecond pulses either with a wavelength of 355 nm scribing a line, colloquially called "the kerf", across the back surface of the wafer or a wavelength of 266 nm for cutting from the face of it [6][7][8][9]. However, this method produces a huge amount of debris. Moreover, the use of nanosecond pulses imposes serious requirements on the cooling system due to wide areas around the kerf which are affected by the heat [10]. In addition, using UV radiation generates health concerns for the personnel handling the system. AbstractThe quality of the reflecting faces after dicing is critical for the fabrication of efficient and stable laser diodes emitting in the green-violet region. However, highquality faces can be difficult to achieve for devices grown on a sapphire substrate as this material is difficult to cleave cleanly. We have therefore investigated a technology known as "stealth dicing". The technology uses a pulsed laser to damage a plane of material inside of the wafer due to multiphoton absorption instead of cutting through the wafer surface. If the damage is induced in a line of stress points, the sample can then be cleaved easily along the damaged plane to leave a high-quality surface. The use of this technique also reduces thermal damage and debris.

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Impact of laser scribing for efficient device separation of LED components

Cited by 21 publications

References 3 publications

Structured beam shaping for precision laser dicing of multilayered substrates

Structured beam shaping for precision laser dicing of multilayered substrates

Laser Fabrication and Machining of Materials

Stealth dicing of sapphire wafers with near infra-red femtosecond pulses

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