Plasma confinement ring improves treatment uniformity

Process temperatures can be kept low because the ring increases etch rate capability without the need to increase the electrode temperature or add bias to the chuck.

Using the confinement ring, there is a free conduction path between the upper and lower electrodes in the wafer region, but no conduction path in the adhesive tape and wafer frame area.

The ring is made with an insulated, non-conductive material, while the aluminium-to-aluminium plasma conduction path is confined to the wafer area. There is a 2mm gap between the ring and the adhesive tape and wafer frame. Because there is no plasma generation or plasma to the bottom of the wafer and adhesive tape, undercutting and delaminating are minimised and there is no sputtering or adhesive tape deposition on the wafer surface.

Director of marketing, Nordson MARCH, Jonathan Doan explained: "The big difference between our concept and most front-end systems is the spacing and confinement method.”

Doan added: "In our method, we minimise the gap between the ring edge and lower electrode, resulting in a smaller spread area. This gap is roughly 2mm or less, so you only get secondary plasma, rather than primary plasma as you do on other systems. The overall chamber volume is reduced to just the area above the wafer."