Better uniformity is probably the biggest benefit. |
Non-uniformity was not a big issue in the past. We typically cranked up the power until we got full removal. Now, however, we have fragile lines that easily damage. The major issue is non-uniformity, where you can have damage on one part of the wafer and zero particle removal efficiency on another part of the wafer. |
One concern is that the cleaning occurs at a certain angle, and you will not get symmetric cleaning on two sides of a trench. |