Self-Limiting Film Growth of Transparent Conducting In2O3 by Atomic Layer Deposition using Trimethylindium and Water Vapor

Conformal and self-limiting film growth of transparent conducting In 2 O 3 is demonstrated with atomic layer deposition (ALD) using trimethylindium (TMIn) and water vapor. Various parameters, including pulsing times of TMIn and H 2 O and deposition temperature, are varied to confirm the ALD processing window of In 2 O 3 . It is found that an extremely large Langmuir exposure of H 2 O (∼2 Torr s) is required to fully react the surface-adsorbed In-(CH 3 )* groups with H 2 O. Self-limiting film growth is obtainable at the deposition temperatures between 200 and 251 °C where the film growth is controlled by surface adsorption of TMIn molecules. Within the ALD window, ALD-In 2 O 3 exhibits a film growth rate of ∼0.039 nm/cycle at 217 °C. In addition, the film exhibits an excellent step coverage of ∼97% on a high-aspect-ratio (∼11) nanostructure. The resistivity of the ALD-In 2 O 3 film deposited at 200 °C is about 2.8 × 10 –3 Ω cm, and this is attributed to the high Hall mobility of 84 cm 2 /(V s). Finally, the reduction of the Hall mobility of the films with respect to increases in the deposition temperature is correlated to the evolution of microstructures.