Plasma modeling of a PEALD system for the deposition of TiO ₂ and HfO ₂

Abstract

A PEALD (plasma enhanced atomic layer deposition) system is developed and analyzed by using a fluid model in 2-D ICP (inductively coupled plasma) was used as a remote plasma source on the top of an Al deposition chamber for handling 200 mm wafers. TIIP (titanium isoproxide) and TEMA-Hf (tetraethylmethyl amino hafnium) were used for deposition precursors. Ar-+-O2 and H2O plasmas were used as an oxidant for those precursors. A conventional 100 mm diameter ICP source was replaced with a 33 mm diameter sealed-off glass tube wound with a 6.35 mm-diameter copper tube antenna. The effects of a 300 - 400 W, 13.56 MHz plasma were analyzed by using OES(optical emission spectroscopy) and the properties of the deposited films. The uniformity of the film thickness was very sensitive to the wafer temperature rather than to the plasma parameters for HfO2. Fluid modeling of the plasma showed a 37 mm source had an equivalent radical generating capability as a 100 mm source. The electron density calculated just above the wafer was 1/100 of that in the source region and it could be considered as remote. The heat transfer analysis showed that the rise in the wafer surface temperature could be as high as 100 °C with a large diameter plasma source to give large non-uniformity in the film's thickness for a temperature sensitive precursor like TEMA-Hf.