Paper PS-ThP2
In-situ Plasma Diagnostics Study of a Commercial High Power Hollow Cathode Magnetron (HCM) Deposition Tool

Thursday, October 23, 2008, 6:00 pm, Room Hall D

The development of special plasma diagnostic techniques is required to characterize the plasmas used in physical vapor deposition (PVD) and plasma enhanced chemical vapor deposition (PECVD) commercial tools because of the intense deposition environment, non-standard geometry, and non-standard frequencies. A commercial 200mm INOVA high power (36 kW) HCM deposition tool with computer controlled system was set-up and used as a realistic PVD test bed for designing and testing the new plasma diagnostics techniques. A 3-D scanning RF compensated Langmuir probe was designed, constructed and used to get spatial information of plasma temperature and density in the HCM tool at various input power (0-15 kW), pressure (10-70 mTorr) ranges. Measured electron temperature values are in the range of 1-3 eV and the electron density is between 6×10¹⁰ to 2×10¹² cm^-3. While operating the tool, deposition of metal on the tungsten probe tip and the insulator probe body was observed. In order to sputter away the deposited material from the tip of the probe a self-cleaning in-situ plasma cup was designed. The plasma cup has a side cleaning station so that RF compensated Langmuir probe can be moved into it, cleaned and return to its original condition without being withdrawn from the system. We observed a considerable variation in electron temperature and density values after the probe was exposed in a 2 kW metal plasma for about 10 minutes. After cleaning the probe tip for about 8 minutes we observed a recovery of electron temperature to the initial value, however the measured electron density was not recovered. Further results revealed the importance of other effects such as probe temperature, temperature of the tool and the probe surface condition. The conductivity of the probe body surface decreases with an increase in deposition time. Hence it is necessary to clean the probe body as well as the probe tip to get more reliable plasma parameter values. A new method to clean the probe body in-situ has been implemented and results will be presented. Further experiments have been conducted to find the deposition rates and ionization fraction of the incident metal atom species employing a quartz crystal microbalance combined with electrostatic filters. A full 3-D scan of parameters is presented.

Acknowledgement: This work was supported by an SRC (Semiconductor Research Corporation) contract with Novellus custom SRC funding.