| AVS 56th International Symposium & Exhibition | |
| Plasma Science and Technology | Thursday Sessions |
| Session PS-ThP |
| Session: | Plasma Science Poster Session |
| Presenter: | C. Bevilacqua, Numonyx |
| Authors: | C. Bevilacqua, Numonyx A. Marchelli, Numonyx P. Petruzza, Numonyx G. Fazio, Numonyx |
| Correspondent: | Click to Email |
In a R&D fab, where different processes are performed on the same dry etching hardware, there is a strong need to monitor the status of the chamber, in terms of cross-contamination from the different etching species and their reactions products deposited on chamber walls, which can cause uncontrolled shifts in the processes.
Through this work we validate a new technology method for monitoring and reveal metal elements in dry etch conductor tool.
Changes in chamber wall conditions (e.g., chemical surface composition) are identified as one of the main causes of process drifts leading to changes in the process performance (etch rates, etch profiles, selectivity, uniformity, etc.). This effect is particularly critic when the same chamber is required to sequentially process metals and non-metal elements. Standard control procedures mainly based on XRF technology utilize wafer tests to perform the acquisition measurements with relevant down times and low frequency testing. It is known that different conditions of the chamber walls have great influence upon global system impedance (plasma + equipment hardware), which requires continuous tuning of the RF system in order to maximize the power transfer to the plasma.
The observation of optical emission (performed through a spectrometer directly installed on the tool) from a waferless He plasma allows to detect some variation of impedance due to different chamber conditions.
The choice of He as process gas for this test is mainly due to the fact that it is chemically inert; besides is allows minimum impact on consumable parts inside the equipment. By comparing the test described to standard quantitative technology, we are able to identify a cut off threshold - technology device-dependent - above which the decontamination procedure becomes mandatory.
The new test can be used at the end of each critical process like a waferless autoclean, in order to constantly monitor the status of the chamber and assure a safe and correct lot processing.