Mechanism of high density plasma processes for ion-driven etching of materials

• Published in: Solid-state electronics 1999-09, Vol.43 (9), p.1769-1775
• Main Authors: Lee, J.W., Donohue, J.F., Mackenzie, K.D., Westerman, R., Johnson, D., Pearton, S.J.
• Format: Article
• Language: English
• ISSN: 0038-1101; 1879-2405
• DOI: 10.1016/S0038-1101(99)00129-X

We propose a mechanism for ion-driven etching of materials in a high density plasma (>10 11 cm −3) system. An inductively coupled plasma (ICP) reactor was used to model the etch mechanism. Ion density and plasma potential were measured with a Langmuir probe and the self-induced dc bias simultaneously recorded. Power density (i.e. ion flux times ion energy) was found to be the most influential factor for predicting the etch rate of ion-driven materials, like dielectrics and III-nitrides, especially when running in a high density plasma (HDP) mode. Power density is also shown to be a function of ion mass, ion density, ion charge, dc bias and plasma potential. The relation between these plasma parameters and power density can be correlated with process parameters such as ICP source power, rf chuck power, chamber pressure and gas flow rate. This correlation was modeled with the aid of a design of experiment (DOE) simulation. We have demonstrated the use of a power density model to explain the mechanism responsible for HDP etching of SiO 2, which is one example of a high-bond strength material.