Aluminum-germanium wafer bonding of (AlGaIn)N thin-film light-emitting diodes

作者：Gossler Christian^*; Kunzer Michael; Baum Mario; Wiemer Maik; Moser Ruediger; Passow Thorsten; Koehler Klaus; Schwarz Ulrich T; Wagner Joachim

来源：Microsystem Technologies, 2013, 19(5): 655-659.

DOI：10.1007/s00542-012-1709-4

Eutectic aluminum-germanium wafer bonding was used to fabricate (AlGaIn)N thin-film light-emitting diodes (LEDs). Wafer bonding was carried out on 2aEuro(3) wafer level at a bond temperature of 470 A degrees C using patterned Al bond pads on the GaN-on-sapphire LED epiwafer and plain Ge substrates. The microstructure of the joint formation was characterized via cross-section analysis using scanning electron microscopy and energy dispersive X-ray spectroscopy (EDX). Scanning acoustic microscopy was used to investigate the bond interface. The shear strength was determined to be 1-2 kN/cm(2). The formation of a liquid Al-Ge phase is evident from cross-section analysis and optical microscopy. During solidification, Al and Ge are separated into distinct phases again, which is revealed by EDX. The obtained bond is not free of micro-voids, yet it is mechanically stable and suited for the fabrication of thin-film LEDs by removing the sapphire substrate via laser lift-off, which is also demonstrated.

• 出版日期2013-5