Optimization of UV laser scribing process for light emitting diode sapphire wafers

Abstract

Billions of light emitting diodes ͑LEDs͒ are used today in traffic control, automotive headlights, flat panel display technology, mobile devices, back lighting, projection, and general illumination applications. With the dramatic growth in LEDs, manufacturers are looking for technologies to increase production yield and decrease cost. Sapphire wafer singulation into miniature dies is one of the critical steps used in blue LED manufacturing. Typical dicing techniques used in wafer singulation process include laser dicing, laser scribing and breaking, mechanical scribing and breaking, and diamond blade sawing. In recent years, laser scribing and breaking has proven to be very efficient for volume LED manufacturing. In this paper, we have characterized the effect of 355 nm Q-switched diode-pumped solid-state ͑DPSS͒ laser parameters such as fluence, pulse width, and repetition rate on laser scribing process by measuring sapphire wafer cutting depth and scribe kerf width. Furthermore, we have also explored the techniques to increase process efficiency while maintaining quality of scribes using different laser sources.

Al Doping of CsLiB6O10for High Resistance to Ultraviolet-Induced Degradation

“…olid-state ultraviolet (UV) lasers that employ frequency conversion are attractive for high-resolution inspection and advanced material processing. 1,2) CsLiB 6 O 10 (CLBO) is an excellent nonlinear optical crystal for generating high-power UV output with wavelengths below 300 nm. [3][4][5] For high-repetition-rate pulsed lasers with a wavelength of 266 nm, we have recently found that UV output degradation and beam distortion in CLBO occurred at a lower peak power density than the bulk laser-induced damage threshold (LIDT).…”

Solid-state femtosecond UV lasers: recent advances and challenges

“…An excellent example is a rollable AMOLED display fabricated by ink-jet printing and laser lift-off technology, which is very promising for manufacturing large-size flexible AMOLED [6]. Semiconductor industry applications such as wafer scribing and dicing [7], micromachining of GaN [8], and extreme ultraviolet photomask repair [9,10] also highly benefit from femtosecond UV laser development. Other fields of applications where femtosecond NUV and DUV sources are used and have huge potential are medical device processing [11], direct medical applications [12], glass processing [13] and laser-induced periodic surface structuring [14].…”

Growth of large and high quality CsLiB6O10 crystals from self-flux solutions for high resistance against UV laser-induced degradation

“…here is an increasing demand for high-power deep ultraviolet (UV) sources in industrial fields such as high-resolution inspection 1) and advanced material processing. [2][3][4][5] All-solid-state UV lasers based on frequency conversion are considered to be a promising tool due to their high reliability, low maintenance cost and compact size. The efficiency of the wavelength conversion greatly depends on the characteristics of the nonlinear optical crystal.…”