Surface modification of nanotwinned copper and SiCN using N2 and Ar plasma activation
Rou-Jun Lee, Pin-Syuan He, Dinh-Phuc Tran, Wei-Lan Chiu, Hsiang-Hung Chang, Chang‐Chun Lee, Chih Chen
Abstract
Nanotwinned copper (NT-Cu) and silicon carbon nitride (SiCN) films were modified using N 2 /Ar plasmas to enhance their bonding strength. X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and contact angle analyses were then conducted. The contact angles of the NT-Cu films significantly reduced, dropping from 54.8° to 32.1°, while that of the SiCN sharply declined from 51.1° to under 10°. A significant increase in the Si-O bonds was found in the SiCN after the plasma treatment. These factors thus contributed to the enhanced bonding strength (up to 30 and 27.4 MPa for the NT-Cu/NT-Cu and SiCN/SiCN, respectively). Additionally, we performed the SiCN/SiCN room temperature bonding and evaluated its bonding energy using four-point bending tests. We found that the bonding energy increased from 0.49 to 1.2 J/m 2 after annealing at 100 °C for 30 min. Transmission electron microscopy (TEM) image revealed some nanovoids at the bonding interface as bonded at room temperature. These voids could be eliminated by further annealing at 250 °C for 1 h. This study offers insights into the plasma surface modification to enhance the bonding strength of NT-Cu/NT-Cu and SiCN/SiCN.