A novel vacuum epitaxial lift-off (VELO) process for separation of hard GaAs substrate/carrier systems for a more green semiconductor LED production. (15th November 2017)

• Record Type: Journal Article
• Authors: Englhard, M.; Reuters, B.; Michaelis, F.B.; Behringer, M.; Sundgren, P.; Klemp, C.; Skibitzki, O.; Schroeder, T.
• Is Part Of: Materials science in semiconductor processing. Volume 71(2017)
• Page Start: 389
• Page End: 395
• Publication Date: 2017-11-15
• Subjects: Vacuum epitaxial lift-off (VELO) -- InGaAlP TF-LED -- Reuse GaAs -- AlAs etching -- HRXRD -- μ-PL; Semiconductors -- Periodicals; Integrated circuits -- Materials -- Periodicals; Semiconducteurs -- Périodiques; Circuits intégrés -- Matériaux -- Périodiques; Electronic journals; 621.38152
• DOI: 10.1016/j.mssp.2017.08.029
• Languages: English
• ISSNs: 1369-8001

Abstract

Abstract: This study reports on a novel vacuum epitaxial lift-off (VELO) process to reuse the GaAs substrates in light-emitting diode (LED) production. The method is based on an epitaxial lift-off technique, whose application is however limited to flexible wafers, as gaseous reaction products (e.g. AsH 3 ) formed during the etching of AlAs with hydrofluoric acid are trapped within the wafer stack. In the developed VELO process, an applied vacuum of ∼ 5000 Pa to the bonded wafer stack removes such detrimental reaction gases, allowing a separation of hard substrate/carrier systems. The VELO process is evaluated with a state-of-the-art thin-film light-emitting diode (TF-LED) phosphide-based epitaxial structure with a buried AlAs sacrificial layer and a simplified LED chip construction at 4-in. wafer level. Characterization of the so-processed LEDs using high-resolution x-ray diffraction, μ -photoluminescence and electrical testing reveal that the VELO TF-LEDs show a comparable performance like to released chips by using conventional grinding/polishing and etching of the GaAs substrate. As our VELO process is non-destructive to the substrate, the GaAs wafers can be reused, enabling lower costs for LED production and reduced toxic waste to establish a green semiconductor production.