Title

Utilizing The Transparency Of Semiconductors Via "Backside" Machining With A Nanosecond 2 Μm Tm:Fiber Laser

Keywords

Infrared lasers; Semiconductors processing

Abstract

Semiconductors such as Si and GaAs are transparent to infrared laser radiation with wavelengths >1.2 μm. Focusing laser light at the back surface of a semiconductor wafer enables a novel processing regime that utilizes this transparency. However, in previous experiments with ultrashort laser pulses we have found that nonlinear absorption makes it impossible to achieve sufficient optical intensity to induce material modification far below the front surface. Using a recently developed Tm:fiber laser system producing pulses as short as 7 ns with peak powers exceeding 100 kW, we have demonstrated it is possible to ablate the "backside" surface of 500-600 μm thick Si and GaAs wafers. We studied laser-induced morphology changes at front and back surfaces of wafers and obtained modification thresholds for multipulse irradiation and surface processing in trenches. A significantly higher back surface modification threshold in Si compared to front surface is possibly attributed to nonlinear absorption and light propagation effects. This unique processing regime has the potential to enable novel applications such as semiconductor welding for microelectronics, photovoltaic, and consumer electronics. © 2014 SPIE.

Publication Date

1-1-2014

Publication Title

Proceedings of SPIE - The International Society for Optical Engineering

Volume

8968

Document Type

Article; Proceedings Paper

Personal Identifier

scopus

DOI Link

https://doi.org/10.1117/12.2040306

Socpus ID

84900539866 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/84900539866

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