Chamber Conditions Control with Waferless Auto Clean Strategy in BEOL Aluminum Metal Etching Process

Waferless auto clean (WAC) has been used to clean the chamber after each wafer. However, unsuitable etching chemical reactions and post process WAC will change the chamber conditions to induce the etch rate drift or fall-on particle issues. In this paper, CH<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf> is proposed to replace N<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> in BEOL aluminum metal etch. A series of experiments are taken to enhance the insitu WAC efficiency. As a result, a stable and reliable manufacturing process can be achieve through the optimum of etch chemistry and WAC time.