Low Damage In-Situ Contact Cleaning Method by a Highly Dense and Directional ECR Plasma

Abstract

In situ electron cyclotron resonance (ECR) plasma cleaning process is applied for the cleaning of sub-half-micron-sized contacts in dynamic random access memory (DRAM) devices. ECR plasma cleaning shows superior performance over reactive ion etch (RIE), RF plasma, and dilute HF wet cleaning methods. The high density but low incident energy of the ECR plasma process minimizes surface damage. In addition, the high directionality of this process effectively removes surface impurities from sub-half-micron-sized contacts, resulting in low and stable contact resistance. The ECR plasma cleaning process also reshapes the contact profile in favor of contact filling by Al reflow and is extremely effective for contact cleaning, especially when H 2 is incorporated to the ECR plasma cleaning process. Thus it shows great promise as a future contact cleaning technology of choice.