Design considerations for low damage process plasmas

Low ion energy is accepted as an essential requirement in achieving low dam age when dry etching semiconductors. In order to investigate whether low en ergy is sufficient we have studied the effect of a real SiCl4 reactive ion etching system as well as the effect of bombardment of separate constituent ions from a SiCl4 discharge in an low energy implanter. We find that molec ular ions contribute less to deep damage than do atomic ions. Thus low dama ge may be promoted by using reactive etch chemistries with low ion energies and small atomic to molecular ion fractions.