Combined Surface Activated Bonding Technique for Low-Temperature Cu/Dielectric Hybrid Bonding

Abstract

Cu/dielectric hybrid bonding at low temperatures of no more than 200°C remains challenging because of the different features of Cu-Cu and dielectric-dielectric (such as SiO2-SiO2) bonding. This paper reports a combined surface activated bonding (SAB) technique for low-temperature Cu-Cu, SiO2-SiO2, and SiO2-SiNx bonding. This technique involves a combination of surface irradiation using a Si-containing Ar beam and prebonding attach-detach process prior to bonding in vacuum. Wafer bonding experiments were conducted at either room temperature or 200°C. Results of bonding strength measurements, transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS) observations, and X-ray photoelectron spectroscopy (XPS) analysis were reported and discussed to understand the present combined SAB technique.

Diamond as the heat spreader for the thermal dissipation of GaN-based electronic devices

“…To overcome these issues, a low temperature bonding technique was developed. The low temperature wafer bonding is successful in various applications such as the fabrication of silicon-on-insulator (SOI), heterogeneous integration, and advanced packaging at temperature below 400 °C [40,41]. One approach at room temperature is to employ the surface activated bonding machine, in which the Ar ion beam at high power was used to active both the surfaces and a Si nano-layer was sputtering deposited as the adhesion layer [42].…”

Anti-oxidant copper layer by remote mode N2 plasma for low temperature copper–copper bonding

“…One such approach is removing the native oxide film that has already formed on a Cu surface. This approach includes a surface activated bonding (SAB) method 13 , 14 that breaks the Cu oxide layer and activates the Cu surface using collision from a high energy Ar beam and a wet treatment method 15 , 16 that chemically removes the Cu oxide layer using various acids, such as sulfuric acid (H 2 SO 4 ), acetic acid (CH 3 COOH), and citric acid (C 6 H 8 O 7 ). Alternatively, there is a way to prevent Cu oxidation from the beginning.…”

Low-Temperature Co-hydroxylated Cu/SiO2 Hybrid Bonding Strategy for a Memory-Centric Chip Architecture

“…40 On the contrary, the bonding mechanism of the hydroxylated Cu surface was not just based on atom diffusion. Since sufficient −OH groups were established on smooth Cu and SiO 2 surfaces using FA → Ar/O 2 activation, a dehydration reaction similar to reaction (reaction 4) occurred first between the Cu−OH structures at low temperature: 41…”