Laser controlled thermocracking die separation technique for sapphire substrate based devices

Abstract

PACS 65.40.-b, 78.20.-e The glass precise cutting by CO 2 laser appeared to be effective for sapphire wafer die separation. A standard sapphire wafer can be processed in 2 min, neither thinning, no final cleaving are needed. A commercial equipment LED chip cutting demonstrated no degradation after 5000 h of the LED test. IntroductionThe traditional mechanical die separation is not well suited to sapphire substrate devices, mainly using c-oriented sapphire surfaces. Meanwhile the cutting process, described in this manuscript, for other sapphire surface orientations is effective as well. The laser ablation for cutting was successfully demonstrated by Emcore, K-Jet International Inc. and J. P. Sercel Associates Inc. companies [1]. They use a high power UV laser for sputtering grooves into the sapphire substrates, followed by conventional scribe and break methods. Compared with the mechanically scribing with a diamond tool the UV method increases die yields and wafer throughput and reduces the equipment operation and maintenance costs. Meanwhile the cost and the lifetime for the UV laser are still subject for further development. Moreover, the technique described in this paper allows to get rid of the fracturing machine cleaving and even the wafer thinning if needed. The quality of the cutting edge appeared to be effective mirrors for laser dies. We used for GaN-based LED wafers the Laser Controlled Thermocracking Die Separation Technique with the laser wavelength 10.2 µm. The Laser Controlled Thermocracking Technique (LCTCT) [2] is widely used for the precise cutting for flat panel display production, including liquid crystal displays and plasma display panels [3].

Narrow-aperture electron beam in the forevacuum pressure range as a tool for dimensional processing of silica glass

“…The technology of laser controlled thermal splitting can be applied for cutting thin glass products with maximum thickness of 3 mm [4]. Whereas electron beam treatment can be effectively used for performing operations with thick-wall silica glass products and products with complex shape, as well as for removing shortcomings of the existing treatment methods [5][6][7][8].…”

Narrow-aperture electron beam in the forevacuum pressure range as a tool for dimensional processing of silica glass

“…The technology of laser controlled thermal splitting can be applied for cutting thin glass products with maximum thickness of 3 mm [4]. Whereas electron beam treatment can be effectively used for performing operations with thick-wall silica glass products and products with complex shape, as well as for removing shortcomings of the existing treatment methods [5][6][7][8].…”

New Laser Cutting Technology of Sapphire Wafers on Crystals

“…The first attempts to use the LCT method for cutting instrument sapphire plates to crystals in the production of light-emitting diodes have shown its indisputable advantages and prospects [3].…”