Comparative study of wafer-scale Al2O3 layers made by thermal and plasma-enhanced ALD

Inhalt:
In this comparative study a thermal and a plasma assited atomic layer deposition (ALD) process of aluminumoxide (Al2O3) are presented. Each process takes place in the same ALD reactor using a trimethylaluminium (TMA) precursor using ozone or a capacitively coupled remote oxygen plasma (R-CCP) as oxidant respectively. The resulting film thickness and uniformity was determined by spectroscopic ellipsometer measurements and the dielectric properties of the films were evaluated by CV and IV-measurements of metal insulator semiconductor (MIS) capacitors. They reveal for both processes excellent relative permittivities around 8 and a breakdown voltages above 7 MV/cm. Standard deviations of thickness around 3% qualify these processes even for industrial fabrication.