Method of high density plasma etching for semiconductor manufacture

摘要

An improved method of high density plasma etching for etching substrates such as semiconductor wafers is provided. The method includes controlling the ratio of ions to neutrals in a high density plasma using an ion filter located in the flow path of the plasma. The ion filter is adapted to interrupt and deflect ions in the plasma while allowing neutrals to pass through to the substrate unaffected. This helps to prevent notching because a more favorable ion/neutral ratio is present at the substrate. At the same time etch selectivity is high, particularly for etching polysilicon to oxide, because current density can remain high.