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Volume 32, Issue 1, January 2014
The material composition and the Si surface passivation of aluminum oxide (Al 2O3) films prepared by atomic layer deposition using Al(CH3)3 and O3 as precursors were investigated for deposition temperatures (T Dep ) between 200 °C and 500 °C. The growth per cycle decreased with increasing deposition temperature due to a lower Al deposition rate. In contrast the material composition was hardly affected except for the hydrogen concentration, which decreased from [H] = 3 at. % at 200 °C to [H] < 0.5 at. % at 400 °C and 500 °C. The surface passivation performance was investigated after annealing at 300 °C–450 °C and also after firing steps in the typical temperature range of 800 °C–925 °C. A similar high level of the surface passivation performance, i.e., surface recombination velocity values <10 cm/s, was obtained after annealing and firing. Investigations of Al 2O3/SiNx stacks complemented the work and revealed similar levels of surface passivation as single-layer Al 2O3 films, both for the chemical and field-effect passivation. The fixed charge density in the Al 2O3/SiNx stacks, reflecting the field-effect passivation, was reduced by one order of magnitude from 3·1012 cm−2 to 3·1011 cm−2 when T Dep was increased from 300 °C to 500 °C. The level of the chemical passivation changed as well, but the total level of the surface passivation was hardly affected by the value of T Dep . When firing films prepared at of low T Dep , blistering of the films occurred and this strongly reduced the surface passivation. These results presented in this work demonstrate that a high level of surface passivation can be achieved for Al 2O3-based films and stacks over a wide range of conditions when the combination of deposition temperature and annealing or firing temperature is carefully chosen.
Selective atomic layer deposition of zirconia on copper patterned silicon substrates using ethanol as oxygen source as well as copper reductant32(2014); http://dx.doi.org/10.1116/1.4826941View Description Hide Description
The authors report a new chemical approach for the selective atomic layer deposition of ultrathin layers of zirconium oxide (ZrO2) on copper patterned silicon surfaces. Instead of using common atomic layer deposition (ALD) oxygen sources such as water, oxygen, or ozone, the authors use ethanol, which serves as oxygen source for the ALD on the silicon side and as effective reducing agent on the copper side, thereby selectively depositing ZrO2 film on the silicon surface of the substrate without any deposition on copper up to at least 70 ALD cycles. The resulting ZrO2 nanofilm is found to be an effective copper diffusion barrier at temperatures at least up to 700 °C.