A copper liner is a glue-like transition layer that helps deposited copper adhere and connect to underlying copper lines.

“The liner is, think of it almost like a glue layer or transition layer that we need in order to deposit the copper and have it stick-”

“... and make that connection to the copper lines below it. These are all interlocking copper lines that interconnect to each other. But every time you deposit copper, you've always had a, a liner underneath it, and in the past, that liner may have been a significant portion of the entirety of that conduction path.”