Growth condition of amorphous ZTO films from rotatable targets

• Industrial scalable ZTO and GZTO rotatable targets were produced.
• Position resolved the evaluation of electrical and optical properties.
• Simulation of negative charged oxygen ions to evaluate the process damage of the film.
• Prevention of film damage due to optimized growth conditions

In the last years, amorphous oxide films like indium gallium zinc oxide (IGZO) received increasing attention as channel layers in thin film transistors (TFTs). First IGZO-based devices are being successfully introduced into the display market. However, there is also a strong interest to replace or substitute the resource-limited indium. Additionally, alternative oxide materials are being explored. A promising candidate is zinc-tin-oxide (ZTO) with similar properties and performance as IGZO. Typically, indium containing materials are more stable against plasma damage during the sputtering process. Therefore we studied the growth mechanism of ZTO films sputtered from novel rotatable oxide targets both experimentally and through particle-in-cell Monte-Carlo (PIC-MC) plasma simulation. Static imprints are deposited and characterized in terms of electrical and optical performance distribution in order to understand the mechanisms of plasma damage. By PIC-MC plasma simulations, possible origins of plasma damage such as negative oxygen ions are revealed and compared with the experimental data. The comparison of experimental and simulated data allows for designing improved coater geometries with respect to reduced plasma damage and increased film uniformity.