Field
Implementations of the present invention generally relate to methods for cleaning etch hardware used in semiconductor manufacturing applications.
Description of the Related Art
Reliably producing sub-half micron and smaller features is one of the key technology challenges for next generation very large scale integration (VLSI) and ultra large-scale integration (ULSI) of semiconductor devices. However, as the limits of circuit technology are pushed, the shrinking dimensions of VLSI and ULSI technology have placed additional demands on processing capabilities. Reliable formation of gate structures on the substrate is important to VLSI and ULSI success and to the continued effort to increase circuit density and quality of individual substrates and die.
When forming these features, an etch process using a photoresist layer as an etching mask is often utilized. An edge-ring can be used to control the region of the substrate available to the etchant. Typically, etchants accumulate at the exposed substrate surface near the edge-ring, which can lead to over-etching of that region (also referred to as edge roll-up). Wafer edge etch-amounts (EAs) are controlled using a Nickel edge-ring (Ni-ER), placed around the wafer. Metallic Ni removes excess etchants near wafer edges by acting as a chemical catalyst, which quenches excess etchants.
Some production wafers, however, contain variable amounts of metal compounds, such as TiN. Even in etch processes with a good selectivity towards these compounds (e.g., greater than 500:1), small quantities can be etched during the Si etch process. Airborne Ti species get deposited on chamber parts, such as aluminum components of the process kit and the Ni-ER. The Ti can then affect the catalytic activity of Ni-ER, thus preventing the protective activity of the Ni-ER. Loss of ER catalytic activity can lead to strong Si etching near the wafer edge and poor etch uniformity on Si films, which can include a non-uniformity percentage of 12% or higher.
Some have attempted to recover the etch profiles by high temperature bake-out of the contaminated components (e.g., baking at temperatures of 160° C.) and parts wipe-down (e.g., using wet and dry wipes) without success. Other options include replacing all component parts and edge ring with new components. However, replacement of components is both time consuming and not cost effective.
Therefore, there is a need in the art for methods of cleaning or restoring the activity of etch chamber components.