Method for forming an adhesion buffer layer on the walls of high aspect ratio through-holes of an insulating substrate

A method for forming an adhesion buffer layer on the walls of high aspect ratio through-holes of an insulating substrate, comprising the steps of:

• (a) preparing a high-power impulse magnetron sputtering system, having a sputtering chamber;
• (b) arranging a plurality of metal targets in the sputtering chamber;
• (c) fixing the insulating substrate with a plurality of high aspect ratio through-holes in the sputtering chamber by a rotary fixture, wherein the aspect ratio of each of the high aspect ratio through-holes is greater than 4;
• (d) evacuating the sputtering chamber to reduce the pressure inside the sputtering chamber to below 5×10−5 torr;
• (e) introducing an argon gas into the sputtering chamber;
• and
• (f) depositing the adhesion buffer layer on the inner walls of the high aspect ratio through-holes by a high-power impulse magnetron sputtering process for a subsequent hole-filling process to fill the high aspect ratio through-holes with a conductive metal, wherein each of the metal targets is composed of at least one of copper, titanium, chromium, zirconium, tungsten, aluminum, molybdenum, tantalum, yttrium, nickel, gold, silver and platinum, and in the high-power impulse magnetron sputtering process, the sputtering power of each of the metal targets is between 0.5 kW and 5 kW.