New Method to Correlate Crystalline Orientation and Sputtering rate of Tantalum
Thursday, October 18, 2007, 5:30 pm, Room 4C
Normally, higher target sputtering rates contribute to higher film deposition rates, which result in increased throughput. Optimizing the cathode design of sputtering tool and the sputtering parameters are common ways to increase film deposition rate. Controlling the grain orientation of the sputtered material is another possible approach to increase the deposition rate. In order to find the desired orientation for higher sputtering rates, the correlation between crystalline orientation and sputtering rate must be identified. In the past, single crystals were used to correlate the crystalline orientation and sputtering rate. This technique was time-consuming regarding sample preparation and limitations on material availability. The new method uses Electron Backscatter Diffraction (EBSD) to identify the orientation of the individual grains on a polycrystalline material prior to being sputtered. By measuring the change in eroded depth of each grain as a function of sputtering kWh, the sputtering rate is obtained, In order to gather higher grain population and ensure the eroded depth of the individual grains are measurable by a height gauge, the grain size diameter is controlled in the range of 3mm to 20mm. This study used a 4 inch diameter by 0,25 inch thickness polycrystalline Tantalum as a test sample to correlate the grain orientation and sputtering rate. By applying 1 kW power with 10 mtorr Ar pressure, the eroded depths of the individual grains at the erosion zone were measured at intervals of 5 kWh. The results showed that the (111) grain orientation has the lowest erosion rate, while the orientations with higher indices tend to be eroded faster. This study demonstrated that the relationship of crystalline orientation to sputtering rate can be easily established by sputtering polycrystalline materials with the assistance of EBSD to pre- identify the orientation of the individual grains. Copyright 2007. Praxair Surface Technologies. All rights reserved.