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摘要
A scrupulous cleaning and degreasing of the deposition chamber allows to make a ZrN film with stoichiometry of 1.3 and to achieve a level of oxygen contamination equal to 5%. This film exhibits a low number of carriers estimated at N* = 3 x 10(21) cm(-3) and with a very high electrical resistivity value of about 10(5) mu Omega.m. This result points the way for further improvements in the quality of the material.
This amount of oxygen contamination may be reduced in conditions in which only the oxygen will be removed without disturbing the zirconium presence in the film. A bias voltage value between 8 eV and 20 eV reduces the oxygen contamination.
The ionic assistance is often proposed as a mean to minimize the oxygen contamination. However, one must consider the negative phenomena as re-sputtering, ion implantation, atom displacement and stress generation that introduce defects in the film and affect its properties. This work proposes a very low bias voltage value to control oxygen contamination. The bias voltage value is chosen higher than the nitrogen sputtering threshold energy and lower than the argon sputtering threshold energy. The re-sputtering phenomenon, far from being a problem, can be used to achieve the stoichiometry if one starts from a nitrogen-rich compound. In this way, ZrNx is grown with x about 1, with an effective free electron concentration N* = 8.9 x 10(21) cm(-3). Furthermore its resistivity value is about 2 mu Omega . m and the oxygen Secondary Ion Mass Spectrometry (SIMS) signal is similar to the noise signal.
- 出版日期2012-1-25
