An ultra-thin SiO2 ALD layer for void-free bonding of III–V material on silicon

• An ALD SiO2 layer is proposed for InP on Si bonding.
• The ALD SiO2 layer activation with hydroxyl groups is measured by XPS.
• The ALD SiO2 layer activation is evidenced by bonding an InP membrane on Si at 300 °C.

Hybrid bonding of III–V layers on silicon is demonstrated implementing an ultra-thin SiO2 atomic layer deposited – ALD – layer as the intermediate bonding layer. X-ray photoelectron spectroscopy characterization of the SiO2 layers evidences that the plasma enhanced – PE – ALD process activates the surfaces with OH dangling bonds. These dangling bonds ensure the surface activation which is necessary for oxide-mediated bonding. The optimized ALD process parameters have been established in order to produce a void-free InP/Si hybrid interface. This hybrid interface is structurally and mechanically characterized. ALD processing is of great interest for hybrid bonding on Si since it offers simultaneously three advantages: a very thin and controlled thickness, an activated surface and a conformal deposition when already patterned silicon layers have to be considered within operating devices.

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