<title>How to etch the optimal silicon trench: profile development and process discussion</title>

The formation process for trench capacitor etching and its mechanisms in single-crystal silicon with a Cl2/SiCl4 reactive plasma using a multi frequency discharge etch reactor is developed. Trenches are etched using a SiO2 mask on wafers with 150 mm diameter. The influence of process gas flow, pressure, rf-power levels, and temperature is investigated revealing relevant process mechanisms. Attention is paid on the uniformity, reproducibility, and long term stability of the process. Determining the process window by varying the process parameters the changes in trench shapes are investigated giving access to the possibility of a sensitive control of the desired trench profile. The trench profiles achieved under our process conditions meet all requirements demanded by the application in advanced production lines.