Effect of sputtering process parameters on the uniformity of copper film deposited in micro-via

With the increase of the density of interconnecting technology for chip packaging, it is required to form smaller vertical interconnect micro-via in insulating dielectric materials with advanced packaging technology. However, a continuous and uniform copper film cannot be formed on the sidewall of the micro-via after plasma etching due to the exis-tence of the undercut at the top of the micro-via. This paper has developed an inter-connecting process for depositing copper film in 5-10 mm polyimide micro-via based on DC magnetron sputtering technology and investigated the effect of sputtering process pa-rameters on the uniformity of copper film deposited in micro-via. It is found that sputtering power, bias voltage and working pressure have a great influence on the uniformity of the deposited copper film at the sidewall of the micro-via, and these parameters will lead to the deposition gap. In contrast, the rotating speed and deposition time have little influence on the uniformity of copper film deposited on the micro-via, and there is no undeposited phenomenon on the side wall of the micro-via. When sputtering power is 50 W, bias voltage is-70 V, working pressure is 4 mtorr, rotating speed is 10 rpm, and deposition time 5000 s, the wall, bottom and top of the micro-via are covered by continuous copper film, and the copper film on the sidewall is continuous and homogeneous. The optimised pro -cess parameters can be sputtered in the micro-via with a diameter of 5-10 mm.(c) 2023 Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

This paper investigates the effect of sputtering process parameters on the uniformity of copper film deposited in micro-via using DC magnetron sputtering technology. It is found that sputtering power, bias voltage, and working pressure significantly influence the uniformity of the deposited copper film, while rotating speed and deposition time have less impact.