AVS 46th International Symposium
    Plasma Science and Technology Division Tuesday Sessions
       Session PS-TuM

Paper PS-TuM8
X-ray Photoelectron Analysis of Sidewall Passivation Films formed during Sub 0.1 µm Silicon Gate Etch Processes

Tuesday, October 26, 1999, 10:40 am, Room 609

Session: Plasma-Surface Interactions I
Presenter: L. Desvoivres, France Telecom-CNET
Authors: L. Desvoivres, France Telecom-CNET
L. Vallier, France Telecom-CNET and CNRS
O. Joubert, France Telecom-CNET and CNRS
Correspondent: Click to Email
As integrated circuits dimensions are rapidly scaling down to 0.1 µm regime and below, the critical dimension (CD) control of the etched features becomes more and more challenging. The critical dimension budget (10% of the nominal dimension) is usually shared between lithography and etching. Each individual step should be carefully optimized. For silicon gate applications, CD variations across the wafer are usually attributed to etch non-uniformities. However, the passivation layer which forms on the silicon sidewalls has also a direct impact on CD control since the passivation layer thickness is aspect ratio dependent. In the future, a careful control of the nature and thickness of this layer will become critical. In this work, we have investigated the impact of the chemistry (hydrogen bromine, chlorine with different oxygen dilutions) and of the plasma conditions on the formation of the sidewall passivation film. This study has been performed in a high density plasma Helicon source, operated at low pressure. The sidewall film has been analyzed using x-ray photoelectron spectroscopy. The sidewall passivation film formed in 125 nm L/S features is a 2 nm thick SiO@sub 2@ like film composed of oxygen, halogen and silicon. This film is mainly formed during the main etch step of the process thanks to etch products deposition on the sidewalls of the features. It gets oxidized at the very beginning of the overetch step thereby allowing halogen to be desorbed and the oxygen concentration to be increased. The impact of the plasma operating conditions and chemistry on the nature and thickness of the sidewall film will be presented. @FootnoteText@ @footnote 1@ This work has been carried out within the GRESSI Consortium between CEA-LETI and France Telecom-CNET