Design considerations for low damage process plasmas

Low ion energy is accepted as an essential requirement in achieving low damage when dry etching semiconductors. In order to investigate whether low energy 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 molecular ions contribute less to deep damage than do atomic ions. Thus low damage may be promoted by using reactive etch chemistries with low ion energies and small atomic to molecular ion fractions.