Paper PS-TuP13
Analysis of High Aspect Ratio Contact Etch using High Flow Concept

Tuesday, October 16, 2007, 6:00 pm, Room 4C

As contact sizes scale down below 100nm, high aspect ratio contacts (HARC) encounter the limits such as the low selectivity of the resist material, etch stopping mechanism, the profile distortion, and so on. The high flow concept is a widely used scheme for RIE (reactive ion etching) technology. The rapid movement of reactive ion sources affect on the dissociation mechanism of the etching chemistry. The carbofluoride (CxFy) chemical sources show different behaviors, while the flow rate changes at the same pressure. The QMS (quadrapole mass spectroscopy) method enables the analysis of the dissociated chemicals and the byproducts during HARC etch. The ratio of carbofluoride and fluorine seem to be the major factor which determines the profile of HARCs and the resist selectivity. The contact patterns with an aspect ratio of 30 are used to identify the high flow concept in this experiment. The flow rate of carbofluoride chemistry changed up to 2.8 times higher than the normal reference flow rate in a CCP (capatively coupled plasma) chamber. The higher flow rate improves in terms of the resist selectivity. However, the profile distortion between the top opening and the bottom opening is worse than the profiles under the normal condition. The HARC etch study at the high flow condition will be shown in terms of the profile distortion and the real time chemistry monitoring using QMS method.

Keywords : RIE, HARC, high flow.