Plasma Etching of Polysilicon

• Polysilicon etch is the most important etch process as it defines the gate for transistors.

• Polysilicon etch is also used to form stacked capacitor in DRAM chip processing.

• Cl₂ is used as the main etchant. In plasma chlorine atoms break to generate free chlorine radicals that are very reactive and can react with silicon to form gaseous silicon tetra chloride.